Putting Posts in Side Menu?

So I am pretty new to website making. I currently have a 1 year old website that is PR2, and has 700 pages, and 0 posts. My friend that is (a little) better than me at SEO stuff told me the importance of making posts instead of pages. After doing some research I quickly agreed, but now I faced the fact of having to convert 700 pages into posts. As of now, I have my pages set up in the side menu in an acordian menu. I need those pages converted into posts; I figured I have to put the posts in categories.. but the posts are displayed all on one page instead of separately like the pages do. I started doing it (and kind of messed things up) then I tried searching google and I got lost from there. My URL is growgreenerguru.com
You can see that I have “How To videos” posted twice, the 1st one is posts that I just made. This is my issue. Thanks to everyone/anyone in advance!