As noted,

85-86 turn the relay on and off. Likely you need the thermo switch for the fan connected in there somehow, as I assume you do not want the fan running all the time.

30-87 are the business end of the relay. One of those two need to hook to the battery (via a fuse) and the other to the fan motor.

http://www.4crawler.com/4x4/CheapTricks/WaterProofing.shtml#FanControl