1 If you used a wood that needs filling then mask off the entire fretboard and use some past filler to fill it in. first rub with the grain then against it. After the filler is dried then rub off the excess with steel wool.

2 If you want to stain it there are many ways to do so, the better ones are to sunburst it or do a stain that shows the contrast in the wood grain. A easy tip for sunbursting is that you work with a lighter dye in the middle and a darker one on the outside, then you blend them together using alcohol. Some people like to finish it up with some yellow dye stain to brighten up the middle.