Hi Candice,
you need to drill out the plastic fret dot markers, I usually use about a 1.5 or 2mm drill. Once you drill through the centre of the existing marker they weaken and usually pop out. If it doesn't come out get a really small phillips screwdriver to try pop it out.
You will need a brad point drill bit to clean out any glue/gunk and check the depth required on a scrap piece of wood. Most dot markers are 6mm or 1/4" (6.35mm) so work out the size of the markers.
Install the new markers a tad proud with a few drops of super glue and sand them flat with the fingerboard