What should my first baby step be with my canon rebel xti 400?

[boBQuincy]

I can either practice framing shots in automatic mode, OR, I can really focus on taking a baby step out of auto into M or P or AV or TV mode.

"There is nothing worse than a sharp image of a fuzzy concept." Ansel Adams

Auto mode will give you good exposures most of the time (Program mode is almost the same but with some additional options). I would let the camera take care of exposure while learning about composition instead of the other way around.