Whether you're about to submit your post, or editing an existing post, you can add tags the same way.

1) Pick any "Suggested Tags" listed. You may notice the option to choose whether the tag is a "General Tag" or an "Artist/Band" tag from a drop-down menu. Choose whichever is appropriate.

You'll see your selected tag move to the "Selected Tags" section of the posting page.

3) After you've chosen all of the suggested tags, you can add a new tag yourself in the "Add Your Own Tags" section. Type the name of your tag in the text box and click the "Add Tag" button. You'll be prompted to choose from "General Tags" "Band Tags" and "Album Tags". Pick the appropriate one.

4) Click "Submit" when you are finished.