At the bottom edge of your Team Page is a list of links. The first one, on the left, says Sign In. Click it and sign in.
To add riders, just click the beige Add Item button between the list and the photo.
To do something trickier, such as change the photo, scroll up to the top white margin of the page. On the right is a cluster of butttons; the first one is a crude icon of a pencil.
Click it. You can now add, edit, and remove images and text, as well as all sorts of other things you can find if you poke around the drop-down Insert menu at the far left of the top white margin. (This menu and other tools are invisible until you click the Edit pencil.)