Changing Font Sizes in Text

I am using the aReview theme for my website and blog. I would like to change the font size on text to 12 pt and 14 pt when desired. How can I do this since there are no selections for font size on my screen.

Hello, the font-size of the theme are using 12pt for the default, if you think this font size need to be increased, you can add this code below using custom css plugin:

  font-size: 16px;

Thanks. By illustration I was able to change to 16pt by going to Appearance, Editor and changing from 14 to 16pt.
Thanks again. Looks so much better.