The custom text links strategy allows you to configure a set of text buttons at the top of your screen. Clicking a button will open up whatever you connect to it (Smart List, Custom screen, Internal page, External link, Timer, Label, Fast Add Button, etc.).
To add new items to the menu, or edit it, you can click on the cog on the top-right that will show up upon hovering the menu.
Clicking on the "Add new item" button you can select what you'd like to add. Keep in mind that in order to add something the corresponding strategy must be turned on.
Once you've added an item you can change its icon and color by clicking on the dot that appears on its left side. These icons and colors will be used if you have chosen "Show icons" and "Colored Text" or "Colored Background".