When on your profile page click on "Edit my rofile". This will take you to the edit profile page that looks similar to the registration page that you used to sign up.

Under the section sporting information you will see three drop down boxes:

 

Click on the down arrow, select your sport and then click on the plus sign to the right of the dropdown box.

To delete the sport, simply click on the blue cross next to the sport you would like to click.

Once you have finished adding and removing your sports simply scroll down to the bottom of the page and click on "Save" .