Someone needs to add more useful information here.
A Locator Agent is used to find players. They want money for that. You need standing to access them. It takes some time for them to search for the player, then you get an Evemail.
I. What are they / What can they do
lvl 1: range
lvl 2: range
lvl 3: range
lvl 4: universe wide and faster than lvl 3.
afterwards they cannot be used for some time (how long? My lvl4 was back up after 30 minutes)
II. How do I find one some agent search site
III. How do I get access to one fly missions for the corp until you get enough standing to access the agent.