topographic maps are the landscape maps with the lines and numbers on them. The lines are called elevation lines, and the numbers correspond to the elevation of that line.

To use it, simply take a clear, sturdy material large enough to fit over the top of the print completely, like a small sheet of plexiglass. Then trim a blank overhead projector transparency (or anything that you want to draw your map on, but it must be transparent) to the size of the print.
Fill the print with water to the first mark, and trace the edge of the water with a marker. Repeat with all of the marks.