Changing fixture date: Each fixture has a calendar icon, clicking it will pull up a calendar. Select the date and time you would like to move the fixture to and click done. This will add a refresh icon next to the date, the next time you refresh the page the fixture will move to the new date.
Changing fixture Block date: Each block of fixtures for a certain day has a calendar icon, you can change the date and time as above however this will move all fixtures in that block to the new date.
Change Fixture Venue: Each fixture is automatically assigned a venue from your competition settings. To change the venue click the grid icon on the fixture, this will pull down a section where you will be able to select a pitch from all available for that sport
Assign a referee to a fixture: As above click the grid icon and select the appropriate referee from the list. Please see the members section for how to add referees.