I'd like to replace the front brakes from a Nissan

If you have average mechanical ability and the right tools, you can do this yourself.

It will be worth it to buy a manual for your car, Haynes or Wilton publish these. You can get them at your local auto parts store, or find one online. Once you get a manual, you'll want to organize yourself by reading over it first, looking for any special tools it says you need, and then getting the right parts beforehand.

Make sure you use jackstands and not the service jack that came with your car.

If this is your first time working on brakes, then do a dry run without taking any brake parts apart. Follow the book for jacking up the car and removing the wheel, and then compare what you see to the photos in the book.

This is just like any other task, if you spend about half of the time planning, you'll be able to anticipate enough problems that the overall job will go quicker than if you just go out and start.

You need to take the wheel off, then remove the caliper from the knuckle once you have the calpier removed with a large pair of channel locks compress the caliper piston with the old pad still in place , remove the old rotor which should just slide off replace it with the new one,replace the pads in the compressed caliper, reinstall the caliper put the wheel back on and presto you are finished but before you put the car in any gear make sure you pump the brake pedal to seat the brakes again because remember you compressed the piston . good luck be safe use jack stands and block your wheels