REPLACING your brake pads sounds fairly intensive but is actually a straightforward job. That said, there are clear safety implications of getting it wrong, so seek guidance from someone more experienced if you're unsure.
Obviously, a workshop manual, the right tools and the correct pads are a starting point.
Some calipers let you replace pads without removing the caliper itself from the disc. Instead you access the pads by removing a plate on the back of the caliper and then a retaining pin through the pads.
The pistons will probably have to be carefully pushed back into the calipers to make space for the new, unworn pads. If you can't do it with your fingers, use a pair of needle nose pliars, with the opposing jaws on opposing pistons. Don't use the pliars between piston and disc, as this will damage the disc. With the pistons pushed back sufficiently, the new pads should slot easily into place and the retaining pin and plate can be replaced.
Sliding calipers usually have to be removed from the disc by undoing the bolts attaching the caliper to the fork leg. Once off, the jaws of the caliper will have to be eased apart and a retaining clip removed to release the pads. Again, pistons may have to be pushed back to accommodate the new pads. Consult the owners manual for torque settings and use a torque wrench when refitting.
In either case, by pushing the pistons back you are likely to have left some space between them and the new pads. Before riding, pump the lever to close it and push the pads up to the disc. If you don't do this, the next time you use your brakes the lever will come all the way to the handlebar without applying any braking pressure on the disc. And that's bad.
In any event, completely satisfy yourself the brakes are working correctly before going anywhere.
Do one side at a time if you have a two-caliper set up at the front.
Here's one showing pads being swapped with the caliper in place.