Yeah, basically what's said above. At the start of the duel, Speed world 1 or 2 is going to be active as a permanent field spell and can't be replaced, destroyed or gotten rid of in any way. Each turn, including the first, both players gain one speed counters up to a maximum of twelve. The rest depends on which Speed World you use, be it two or one. Both have already been explained, so don't see an issue there.