Steem vs Steem Power vs Dollars

I've been reading around and am still not sure I am treating my Steem properly. The goal is to save for a roof for my home right now. Ive converted everything I have, which is like $75 bucks into Steem power. From what I have been reading, this is the best way to save and hang on to steem while accruing interest? Let me put it this way, I still am struggling to understand the flow of Steem/Bitcoin stuff. I've read a good post by alexc called "Now you've been paid in Steem Dollars - what should you do?" I get the general gist of it but can someone please confirm that I am not being an idiot with the little Steem I've earned? Plus at some point, I may want to contribute to a charity or one of the Steemit contests. I believe in investing back into the community as well as saving. I suck at anything math based and feel stupid as heck 9 times out of 10 when it comes to financial dealings.