Replying to rails beat me up

I tried rails today for my first time. Seemed i could get up on top but then i would fall backwards and my feet would slip out from uner me, or my feet would come apart. anyone have any suggestions on this? the 2 rails werent that good either. they were both downhill, not flat. would that make a difference? I went to my arena today and found the perfect slope and pile of snow from the ice to jib in the summer. so if i cant get rails half ass this season, ill work on it over sumer. any tips would be awsome.
MAT