Steve Henry , Jun 15, 2010; 01:29 p.m.
From this and your other post it looks like you need more help at the beginning of the process. First you should shoot in RAW or the largest JPEG your camera will handle. Then check with the printing service to find out what size and file format the image should be for the size print you want. You should learn to resize them yourself. For starters if you're near one, send them to Costco - they do a nice job for an attractive price with a quick turnaround; you can pick them up or have the prints mailed. If you send folks good files you'll get good prints back.