there are no rules per say, just try to easy the game to your level, by removing balls, picking up a cue ball in hand, whatever you have to do, then make it harder as your game becomes stronger, the only thing to keep in mind that if you miss imagine an opponent (the ghost) will come up and clear up the table, which would make a game for him, so if you miss it's 0-1 for ghost. try to beat him. good luck
When comparing yourself to the pros or others, the rules are simple. You get the break and then ball in hand. You either run out (or otherwise legally make the 10 ball) or you lose.
As far as practice goes, there are various ways to alter the standard game, by adding safety play into the mix for instance. But the standard game is as I referred to it above.
You scratch - you lose.
Any legal pocketing of the 10 ball wins (combinations are fine).
10 ball on the break would technically not be a win since it is a call shot game and snapping the 10 doesn't count. But if this is a big issue for you, I for one would consider staking you.
Typical races are to 7-9.