Your dog is jumping for attention. THe best thing is to ignore him/her completely. When he/she stops jumping, treats, treats, treats!
Stay very consistant, but if that doesn't work, try telling him "sit" while he is jumping. If she/he sits, she/he is reinforced the for good behavior. Whatever method you choose to use, she/he will eventually, not jumping(or sitting) will get him treats and positive attention.