Now that that's all settled, David decides to gather all the important people in Israel in Jerusalem. He's got some things to say.
David explains to the crowd that he was building a Temple so the Ark of the Covenant could have a permanent home, but God told him ixnay on the empletay. David's a warrior and God can't have his bloody hands all over his house.
But David explains that God totally decided that he and his descendants from the house of Judah should rule over all Israel. And out of all David's sons, God has handpicked Solomon to take over the reins of the country.
God decided that Solomon would be the one to build the Temple. And as long as Solomon obeys God, the Almighty will be happy and Israel will be happy and the house of Judah is will reign over Israel for ever.
Then David addresses his son directly: Remember, Solomon, stay faithful to God. That is the single most important thing you can do as a king. Don't mess this up. (So much foreshadowing here.)
After these speeches David literally hands the blueprints for the Temple over to Solomon. These plans contain every last detail about the Temple (which David put together with a little help from God). How it should look, what it should be made of, who should do what job. It's all spelled out.