Engine timing

hi,
my head gasket recently went on the motorway the other day. had to get towed home by the trusty AA!
my step dad fixed the problem, the head wasnt cracked but dunno whether it is warped. he put the timing belt back on how it was when he took it off.
after he put everything back in the engine i took the car for a spin and everything was fine until a couple of days later when everytime the car was in first or second gear it felt as though it wanted to stall and was jerkin me all over the place!!my step dad seems to think it is the timing belt and that it isnt timed up properly but he doesnt know how to adjust it.
so just wondered if anyone knows where to find the timing marks on a 1995 punto 50s or how to adjust the timing.

answers and opinions welcome!!

thanks!