There are three places within the Weebly interface to change text colors:
1) under the DESIGN tab at the top of the page, where you decide the format of your SITE TITLE, PARAGRAPH TITLE, PARAGRAPH TEXT, and LINKS. Clicking on the color swatch will lead you to a swatch palette.
Down at the bottom of the swatch palette, there's a white box where you can type in a hex code for a custom color. It must have a hashtag (#) followed by a code of six numbers and/or letters following it. For example, the hex code for black, is #000000, the coral color used on this page is #CC9933. Type in your code and select OK.
2) Select any text within a text block, and click on the capital A with an underline to select a swatch color or type in your own custom color. The method is the same as above.
3) for those familiar with CSS coding, under the DESIGN tab at the top of the page, in the left-hand editing column, under the Change Theme and Change Fonts buttons, there is an EDIT HTML/CSS button. Clicking on that will take you to a split screen editor, where you will be able to change the site's CSS and see a preview of your changes before committing them with the SAVE button.