If your lucky the fuse will be in a readily accessible place. My TV I had to carefully lift the PCB up to access the fuse.
Using a flat blunt object carefully lift out the fuse. Take care not to break the fuse or scratch the PCB underneath. Once you extracted the fuse from the TV set the cover back on so no one accidentally kills themselves.
Take the fuse to your computer and type in any codes. Also look on the PCB for any markings such as Amperage and volts. Hopefully you get lucky and get some info off the fuse/internet.
I went to RatShack and dug through their fuse bins until I found one that matched both the Amps/Voltage and length/size. I had to buy a package of 4 for $3.40. About 3 more fuses than I needed right now.