How do you make a 6foot snooker table level?

it spins on one side of the table it is this one http://www.argos.co.uk/static/Product/partNumber/3350960/Trail/C%24cip%3D1500006228.Sports%2Band%2Bfitness%3EC%24cip%3D1500006298.Snooker%2Band%2Bpool%3EC%24cip%3D1500006302.Snooker%2Btables.htm