Ok, I picked up a structure map from the reservoir by my house, but how can you find ledges, offshore humps, rip rap, creek channels, drop offs,humps, etc. What do these places look like on a map with contour lines?

Generally speaking, the closer the lines are together, the steeper the change in depth/height. The more spread out they are, the flatter the area on the map. You can go into some serious details on how to read a map with contour lines.

http://www.bassresource.com/fishing/Reading_Maps.html

http://www.usc.edu/org/cosee-west/glaciers/HowToReadTopoMaps.pdf

http://www.spn.usace.army.mil/lake_sonoma/topomap.htm