If we don't know God's name, how do we pray?

That's a good question and may account for some of the odd expressions you hear like "the man upstairs." Anyway, let's go back to this first conversation for a minute.
Then the LORD told Abram, "Leave your country, your relatives, and your father's house.

Go to the land that I will show you.
I will cause you to become the father of a great nation.
I will bless you and make you famous.
I will make you a blessing to others.
I will bless those who bless you and curse those who curse you. All the families of the earth will be blessed through you.

There are a couple of things to note. How many "I wills" do you see? I count five. This is God laying out His plan for Abram and He is speaking about what He with all the power in the universe is going to do. Abram is along for the ride, has a front row seat, but this is going to happen regardless of what Abram is capable of doing or not doing.
The path of wisdom is to be careful with the whole "I will" or even "I won't" phrases. Let me give you an example. The most powerful and cool looking created being ever for all time was Lucifer, the disgraced angel we often call the devil or Satan. Check out what he said and it proved to be his undoing.

I will ascend to heaven and set my throne above God's stars.
I will preside on the mountain of the gods far away in the north.
I will climb to the highest heavens and be like the Most High.'
But instead, Satan will be brought down to the place of the dead, down to its lowest depths.

<= = = The devil had the talk, but not the walk?

Yup! He was the most powerful created being in the universe, but not more powerful than God. The amazing thing is people like you and me that at the end of the day are average tend to do this "I will" thing.

There are still two more things I would like to show you.

Then the LORD told Abram, "Leave your country, your relatives, and your father's house.

As I said, Abram was the son of an idol maker and grew up in a nasty city where every perversion existed even though they didn't have Craigslist yet. God is telling him to leave his past behind. My last observation is one of my favorite parts of this story and it is as true today as it was the day God said it.

I will bless those who bless you and curse those who curse you. All the families of the earth will be blessed through you.

The news makes the whole Israel and Palestine situation very confusing. However, as we are going to see, the Jewish people, Israel, are the seed of Abraham and if you want to be blessed support Jerusalem, Jewish people and Israel and if you want to be cursed, curse Jerusalem, Jewish people and Israel. I realize I need to build my case so you can truly believe this, but just put it on the stack for later consideration. Let's get back to the story.

So Abram departed as the LORD had instructed him, and Lot went with him. Abram was seventy-five years old when he left Haran. He took his wife, Sarai, his nephew Lot, and all his wealth--his livestock and all the people who had joined his household at Haran--and finally arrived in Canaan.

<= = = My friend at school, Benjamin told me that Chanukah is a made up holiday so we would have something similar to Christmas.

Christmas is a made up holiday as well, if you read the Christian Bible carefully, Jesus was not born in December. However, while this holiday is not commanded by the Torah, it is a very important story. So when your father tells of the temple being desecrated by the sacrifice of pigs, listen well. The nation of Israel has much in common with the Nationalists and the Chasidim, who banded together to capture, restore and rededicate the temple. You can't walk the streets of Jerusalem seeing the Orthodox and all those young kids that are serving as soldiers without thinking of this holiday dedicated to assimilation of the Hebrew race and suppression of Judiasm.

What's up with the LORD stuff?

LORD in all capitals has a special meaning. It is a kind of TinyURL like you use to make URLs shorter for Twitter posts. Hebrews would use marks to replace the vowels around their consonant letters, such as C, H, K, L, M, for easier texting.

Then in an economic downturn they stopped putting the vowel pronunciation marks around the name of God. The marketing spiel was the name of God is too holy to write or speak, but actually it was to save ink. This movement caught on and within a couple generations no one knew how to pronounce God's name correctly, or how to write it.

All they knew was HWHY. Now, since they read right to left you see something that vaguely looks like HIGHWAY if you add vowels back, they see something to might have looked like YAWEH.

Anyway, left to right, right to left nobody liked any of it and it was decided to substitute LORD for YHWH. The bottom line, the whole world has forgotten the name for God.

G-d DMs Abram

Try to put this in perspective, you are the son of an idol maker and grew up in a nasty city where every perversion, even some that have been lost in the antiquities and only now are being re-discovered on sites like 4chan.

Abram did not thrive as salesboy in daddy's idol shop, but he loved the outdoors and was a going concern with livestock and how. At this point the entourage was over 50 including all the family and servants and the sheep, goat and camel count was over a thousand. And he had his trophy wife, Sarai, top stock arm candy.

One day, Abram was reading his email, and puzzling over a message touting 'Cinco de Mayo intro of NY's 1st kosher tequila: 11 am, 1214 Vanderbilt Avenue, nr Grand Central' with pastrami burritos. When IT happened! God DM'd Abram!

One thing really set Abram apart from every other man walking the earth, he knew God's voice the second he heard it, he did not question or doubt, he did what he was told to do.

Then the LORD told Abram, "Leave your country, your relatives, and your father's house.
Go to the land that I will show you.
I will cause you to become the father of a great nation.
I will bless you and make you famous.
I will make you a blessing to others.
I will bless those who bless you and curse those who curse you. All the families of the earth will be blessed through you.