[AnnaSB]

Your first step will be:

Код:

CreateDynamicRaceCP(-1447.2351,1502.1000,1.7366);

Then on Callback:

Код:

public OnPlayerEnterDynamicRaceCP(playerid, checkpointid)
{
      buycar(playerid);
}

and sorry for the rest cause I cannot understand your way of writing English.
Hope I helped.