Lay the soldering iron along one end of the fret for approximately 10 seconds. This melts any glue holding the fret in place and softens the wood. Pinch underneath the edge of the fret with the pliers and pry it out of the wood. Continue along the fret until you have freed it completely.
Glue any chips that have come up and press them back into place. Leave to dry overnight. Sand smooth using 220-grit sandpaper.
Check the depth and width of the new fret wire tangs -- the pieces that go into the neck. If the tang is too thin to stick, you've bought the wrong fret wire. If it is too thick or the tang goes too deep, use the metal file for trimming to size. You can glue frets in place but it is much easier to pull and replace them later if they are left unglued.
Cut the fret wire to length with the pliers. Each fret is a different length. If the neck is bound (inlay down the edges) your measuring and cutting must be exact. If not, a bit of overhang can be filed off after installation.
Place the guitar neck in the neck support. Make sure that the spot where you're hammering in the current fret is well supported. Cover the neck support with cloth or leather.
Hammer the fret in place, starting at one end and working across to the other. Ensure that the fret is completely settled with no gaps.
File off the rough ends of the frets if your fingerboard is not bound. Crown the frets by polishing -- first with course sandpaper, then finish with smoother sandpaper. Check the alignment with the straightedge. High or low frets in comparison to others will cause buzzing.