On your dashboard you will see any sign up sheets that have been assigned to you.
Clicking on the sign up sheet will bring you to all the available slots for the sign up sheet.
Click the task to sign up.
This will bring you a small pop up, where you will click "sign me up" to sign up for that slot and see other Members who are signed up for that slot.
The slots you have signed up for will be shaded yellow.
In order to remove yourself from a sign-up sheet, you will need to have an e-board Member edit your sign-up.