To change the date of your games, the event that your team is playing must enable the setting that allows teams to self schedule and change game dates.
Step One:
Click the "Team Scheduling" tab at top of your page and click on the name of the event.
Step Two:
On the calendar on the right side of you page, click on a day that you have a game. Click and hold the game you are trying to move and drag the game to the "Unassigned Matches" section at the bottom.
Step Three:
From the "Unassigned Matches" section, click and hold the game your are trying to move and drag the game to a new day on the calendar.
You will now see that a game on the new date.