Could someone help me PLEASE?

ok so im trying to 上传 a video on to youtobe and i made it 由 using Windows movie maker, i published it and used the avi format but when i tried uploading it , the file was too big and was taking forever even though it is only 2 mins long. im very fustraited, i want to know how to make it smaller if possible, if anyone could help it would be great. thanks