OK, let's start with the Relay...86 and 85 is the relay power. so you would attach a hot wire to 86 and the ground wire to 85, this would power the relay when the power was on. making the relay change states, or turn on. These are the terminals where you would attach your door switch.
30 is always the main battery power, for what ever the relay controls, in your case this terminal would come from the battery or fuse panel. 87 and 87A are the NO or NC terminals. These are the contacts that change state, so what ever your controlling, your door solenoid, the leads for these solenoids would attach here. on the NO contacts, that means the contacts are normally open, and when you push the door switch, they energize the relay and the relay contact closes and energizes the 87 or 87A contact, which will energise the door solenoid and hopefully open the door. The door solenoid has two leads, the black would be the hot wire and terminate on the 87 terminal of the relay, the white lead is grounded. Good Luck.