I answered your other post about this, but hadn't included any adult tops in garter stitch.
Garter stitch thread
Since you've asked a couple times now... are you having trouble purling? Here's a few links that might help.
KH purling videos
Lion Brand - Learn to knit
Garter Stitch top
If you knit in the round most of the tops can be knit only and it would look like stockinette till you have to split for the armholes/neck area. You could then either do it in garter for a different stitch effect or use purling and knit for stockinette. Otherwise..I can't really find much that is just garter stitch. In the other thread you asked about the same thing I gave a link to a book that is all knit stitch. That wouldl probably be very helpful.