Edit a player by clicking on the orange icon seen below.
Editing a player will bring up the same menu box that is used when initially creating a new player. Make any desired changes to existing information, or add any information that is missing.
Once all the rosters have been updated, click on "Details" at the top of your screen next to the roster tab to go back to the details page of this participant.
Click the orange "Save Changes" button in the bottom right corner of your screen.