my staffie is 5months old he's lovely but i'm finding it hard to train him he only wee's and poo's in the house,he bites my son and vistors and has ate everthing i don't know what to do with him.

I suggest the best thing you can do is buy a copy of "The Perfect Puppy" by Gwen Bailey. It's full of brilliant advice.
:)

i would do this call the dog whisperer or simply let your son take him on walks about every 2 hours except at night and then let go outside if he bites or tries or shows any signs simply do this get a punishment a flyswatter water bottle or newspaper and wack them on the back or something and say no loud and firm and after that do no pay attention to him for about 10 minutes or so then let him come give you love first or make him an outside dog and do this happily

DOGLOVERSRUS4EVR
we do not know how old old the child is so it is not wise to advise that he takes a dog...esp.an unruly one for a walk.
Guest
he is just a baby...at 5 months old he is probably teething and should be given plenty of things to chew on.As far as house training is concerned you need to go back to basics.He needs to be watched constantly and when he shows signs of needing to toilet he should be put outside with you in attendance.When he relieves himself you should praise him.If he goes indoors make sure all traces of the smell are removed or it will encourage him to go again.When he has to be left I would suggest using a crate.Use it at night and on the times you cannot watch him...but NOT for long periods during the day.
Archer

have you been to training classes with him at all?
is he left alone each day?
have you thought about a crate for when you are not in the house to supervise him (these are not meant for long periods of time),

there are loads of reasons why he could be doing these things, why dont you join guest and then you can give us more information about his day :)