Changing a Theme

I just installed WP and am trying to make changes to a theme that I added to my blog. The theme is “Sporty” and I am trying to increase the size of the text in the blog and also the text color. I am very familiar with CSS but after a dozen try’s am stumped as to where I should make my changes. None seem to take. I am trying to add color: #000; and font-size: 2.3em; but can’t seem to find where I add them. Any help would be appreciated. I have looked at other posts and them do not seem to address where to place them.

Also when I try to make those changes within WP, no such luck.

Again, I appreciate the help. I am new to WP but not new to coding in HTML and CSS.

Scott