The Channels (Categories) and the Tags are used to group and organize your content.
To manage the cannels and tags:
Step 1: Choose Structure > Taxonomy from the toolbar. (
Step 2: Click on the "List Items" button on the vocabulary that you wish to add or edit terms.
Step 3: Click on the "Add term" button to add a new category, or click on "Edit" button to category you wish to change.