Header, and other issues

[abby85]

** Edited, thanks to tutorials **

Hi, I'm very much an amateur so forgive me if the solutions may be obvious.

1) I added an ad to the header but the positioning is off. It's falling below the designated box and going behind the menu. How do I get it into the proper position?

2) I also want to change the "featured posts" section under the gallery to show my latest posts instead and double the number of characters showing.

3) How do I add an additional box under the "videos" box on the home page

Thanks in advance for the help.
http://www.theresourcefulbride.com
Abena