Changing color for text in the main content of a post?

I recently created a wordpress account, and have some experience in css modification/coding. However, wordpress seems to operate a bit differently than I’m used to. And I’m wondering how I can easily change the font color for the main content of a post, as well as the titles for my sidebar content? The color palette option doesn’t seem to solve this for me.

I have a background image I really like, but the font color is just a little too dark for it. Thank you in advance! ^_^