Here are the steps you go through:-
Click on 'Admin' at the top right of the home page.
Enter your username and password. Click on 'Log in'.
Click on 'Clubs' down the left hand side.
Next to where it says 'edit team' click on the down arrow to the left of 'Fetch' to expose the drop down menu of team numbers. (1,2,3 etc)
Click on the team number you want.
Click on 'Fetch'
Alter the date to the date you require in the same format as shown. OR Click on the date and a calendar will pop up from which you can select a date. The only problem with this is that you will have to scroll through from 1999 to the present day!!
Click on 'Add date to Pool'.
Click on 'Save Team'.