Font Size and Post Cutomization

Hi. I am unable to customize the look of my posts. When I create a post, none of the features in my post editor, such as bold take affect. I would like to be able to change the size of the title text, add a subtitle, and change the size and font of the body text. Being able to customize each post differently would be great instead of just changing css for everything. Suggestions? You can view at amandawilleford.com In my test post, I have the body text bold and italicized in my editor, but it doesn't show when published. Thanks