How could I replace the screen glass? (just the glass, not the screen)

you can check on youtube but if you are not skilled or experienced in lcd refurbishing i would leave it to someone who is as the newer samsung lcds are very thin and you need some equipment such as a hot plate and special wire to seperate the glue and a laminating machine to apply the oca sheet and polariser and a bubble removing machine to remove air between the lcd and glass and a mould.

If you have to ask if you need to apply heat you shouldn't be doing it.