Jumping character

How do I make my character climb up a wall and jump 1 time in mid air?

You should review some of the video tutorials, they are very good.
The concept of “double jump” is covered in several of them.

I recall this tutorial dealing with it:

I am not sure exactly what you mean when you say “climb up a wall”. Do you mean like a spider, or do you mean that a character should be able to climb over walls of a certain height, but not others?