"Abram traveled through the land as far as the site of the great tree of Moreh at Shechem. At that time the Canaanites were in the land. The Lord appeared to Abram and said, 'To your offspring I will give this land.' So he built an altar there to the Lord, who had appeared to him." NIV translation
God appeared to Abram and revealed more about His promise. We remember that Sarai was barren and he was an old man, yet God said that he would have offspring. Abram then set up an altar and worshiped the Lord. This is also a reminder that God was giving the land to His children and not to his nephew Lot. Abram was still walking in disobedience and this is a gentle reminder of God's instructions for him.
"From there he went on toward the hills east of Bethel and pitched his tent, with Bethel on the west and Ai on the east. There he built an altar to the Lord and called on the name of the Lord." NIV translation
Why did Abram leave the place where God had appeared to him? Although we are not told why, we see that he did. As Christians, we sometimes do the same type of thing in that we get distracted by things and drift in our relationship with the Lord. The good news is that, just like Abram, we can stop and worship the Lord wherever we are and know that He is there as well.
"Then Abram set out and continued toward the Negev." NIV translation
We see that Abram called on the name of the Lord but we do not have any indication that God told him to move. He did so anyway and headed into the desert.
As Christians, we sometimes do the same type of thing as we may pray and ask for a direction from God but, many times, we do not wait for His answer.
"Now there was a famine in the land, and Abram went down to Egypt to live there for a while because the famine was severe." NIV translation
This great man of faith looked around and did not see how God would provide for him so he headed to Egypt. He saw the famine in the land and his faith failed. We often do the same thing, as Christians, when we face troubles and look to our own efforts instead of listening to God and trusting in Him.