There are two different entrances on the Brooklyn side. The Bedford entrance is closer to the waterfront if you're connection to/from a ferry. The other entrance is on the north side of the bridge a bit farther east at Continental Army Plaza near the intersection of S. 4th and Roebling.

Note that the pedestrian path on the bridge splits. If you're coming from Brooklyn that doesn't matter, but if you're headed to Brooklyn make sure you take the right (southern) path when it splits if you want to go to Bedford and not Roebling.