Somewhat similar situation here. (Though certainly not a first time mower.) Craftsman/Sears seems to be useless unless you want to shell out $5 for a manual. However, like me, I'm assuming it's mainly the engine part of the mower that concerns you. The engine on the mower I'm using is a Briggs and Stratton - took a bit to find the model/type of the engine (It's NOT on the sticker that looks like a model/SN sticker, but stamped on metal just over the muffler - had to watch the "How to find your model #" video on their site. http://www.briggsandstratton.com/
If your engine is a different brand, you'll have to check their site and investigate a bit. Remember, you're looking for their model #, not the mower model #.
Matthew Parsons, October 2007