Setting and using your torque wrench will depend on what type of wrench you have. There are four basic torque wrench types when it comes to adjustables.
Other wrenches, such as dual-beam and similar gauge-type wrenches, are not "set" for a specific torque value, but are instead used until their gauge shows proper pressure has been applied. While this makes them easier to use, it also makes them generally less accurate as they are dependent entirely on the operator's response to an indicator showing a specific torque.
Pneumatic and Electric Torque Wrenches
Both air-powered and electric torque wrenches operate on the same principle with the same gearing in the head to turn the bolt. So although their power source is different, their design and amplification of the power source is the same.
Adjustment is therefore the same as well. Unless the manufacturer has a proprietary setup (not common), the wrench will be adjusted by setting the power input either at the base where the air enters or on top to control the power flow to the motor. This is a simple setting to a specific torque value. Once the value is met, the power is shut off and the wrench ceases operation.
Of the hand wrenches, this is the most common adjustable torque wrench. The operator sets the desired value (usually by twisting the handle) and the wrench then clicks audibly when that value is reached. This usually includes a 3-5 degree "break" where the handle separates from the head momentarily as a secondary indicator.
Are very much like Click Wrenches, but often reset themselves automatically and have a larger break arc (20-90 degrees). These wrenches are reset either manually - via removal from the application and resetting - or automatically by returning the wrench to the point where it broke (upstroke). The latter is popular in automotive shops where a lot of multiple-application torque is used, such as when assembling engine heads and exhaust manifolds.
These break away in the same way Break-Over wrenches do. The difference is how, with the cam-over using a ball and lobe to slip away from the application rather than just going loose. These are very common wrenches in assembly applications.
These are not commonly used in production or to apply torque, but are common in manufacturing as a quality analysis tool. The QA person sets the wrench and uses it to test bolts on already assembled products, double-checking the torque applied. These wrenches reset very quickly.
Split Beam Torque Wrench
Spoke Torque Wrench
Open End Torque Wrench
Preset Torque Wrench
Pneumatic Torque Wrenches