how to biase the relay

Can Anyone Give Me The Hint To Use The 12vdc Single Pole Relay And What Is The Difference Between Stepper Motor And Dc Motor.

12 Volt dc relay will have two terminals which operate the coil.
check with a DMM, will probably have a value of couple of hundred ohms to k Ω.

Then it will have another two or three terminals to the switch contacts.
also check with DMM.
a common point to NO or NC contact.
It will read infinite Ω when open and zero Ω when closed.

stepper motor requires a driver bridge and requires impulses. read other forum posts re steppers.

dc motor will have a commutator and will run when dc is applied.

Pondering about your question,

A relay is basically a remotely controlled switch.

With thin control wires the relay coil can be operated while the relay contacts operate a large current and avoid voltage drop in 12 Volts systems.

Take for example a starter motor in a car.
Imagine running the positive 12 V to your dash, switch it from there , back to the starter motor. Heavy cables, heavy switch and big voltage drops in long cable run.

by means of a relay small wires go to the ingnition, they control the heavy solenoid or relay contacts which operate the starter motor.

An other case is that different voltage levels can be switched too.
For example a 24 volts ac or dc relay may operate a 400 Volts 3 Ø contactor to start a 3 Ø motor or heating elements.

provided that the relay is rated for the correct voltage level and current rating and duty cycle for the equipment to be switched.