The freeze plugs are located on all four sides of the block. The rear plugs are inside the bell housing and the front plugs are under the accessories. The side plugs are commonly used for block heaters, and appear to be recessed circles. The circle is actually a stamped metal disc with a raised edge, or "flange". You can see one in the picture below, above and to the right of the block drain with the red arrow.

Normal procedure to remove a freeze plug is to use a chisel to punch it into the block, turn it sideways, then pry it out with channel locks. The plug is fairly malleable so it will bend as needed to pull out. Be sure to use sealer, and make sure all surfaces are clean.
JazzMan