UPC barcodes should generally NOT be resized.
However, to resize something in Illustrator, select it, click a corner handle and drag. If you want to maintain proportions, hold the shift key down while you drag.
The help files will assist in learning basic operations such as this.
The place I bought the barcodes from said if I needed to shrink to fit my sticker, this was a good program to use. So I have spent the past 2+ hrs trying to figure out how to do it. haha I will try your tip. thanks
Careful Jacob and Scott. Barcodes should never be scaled by more than about 70% depending on printing method.
Scaling should always be constrained (that is without altering the proportions).
However they may nearly always be truncated (with or without scaling).
This can be done either by outlining the barcode font and manually (with the Direct selection tool) moving the top ends of the bars down - or by using a clipping mask.
There are limits to the amount that codes can be truncated by, depending on how and where they are to be used.
I always use the outlining method. It is safer.