Help with KeyWord and Ad plugins

Okay, first let me warn you, I am completely confused on this. I am totally new and even have the “dummies” book and have to admit, cannot find much help in this subject. So I apologize for sounding a bit, well dumb. Here are my questions.

Keyword plugins-Obviously, I want my site to attract more viewers, I downloaded the All In One SEO, not sure what to do now. Is any one willing to go over the steps for me please? Last plugin I installed was the redirectify and all I needed to do was create a folder and cut and paste the code. This plugin doesnt seems as easy. I also want to be sure keywords are not listed on my pages where it can be viewed.

Ad plugins- I have no idea where I would place ads. I am assuming I need a plugin for that? if so, which one? and will it change the layout of my blog?

I guess I am afraid to go on to the next step in fear I might mess up what I already have done-which wasnt easy for me, since I took on something I know nothing about. Any help and in simple terms, would really be appreciated. Thanks in advance!