My puppie snoopie is 9 months old and every time anybody comes in the house he jumps up at them all the time in the end we have to lock him in his house till they have gone has anyone got any help for me thanks

Say his name clearly and loudly when he jumps up at anything, but only one person say his name. If he gets down, give him a treat. He'll soon learn not jumping up is good. Do this every time and it should work but a lot depends on breed etc.

Does the dog know commands such as sit?

Hello Ramside, I have a 11 month old Rottweiler, and when we, my wife and I, brought him to obedience school, we had the same problem. The instructor said "when he jumps up on you to use your knee to bump him in the chest and knock him down while saying NO" As cruel as that may sound, it worked after the 3rd or 4th time.

LOL, notme! You must be more coordinated than I am! The one time I actually connected my knee with the dog, I hit my freshly neutered German Shepherd in the worst possible spot! (He still jumped on me, he was a little slow--he flunked obedience school twice)
For the klutzes among us, another thing that works is to step INTO the dog so you cause him to back up (for big dogs a nudge with your hip helps). Tell him to sit and do not praise, pet or make eye contact until he does. Then bend down to him to reward him.
Tell guests to totally ignore the dog when they enter the house, and keep the dog on lead at first. When everyone is settled, then let him loose and allow him to greet guests. They may only acknowledge the dog when he greets them politely.