I am a mechanic and yes it is very simple to do but the shop will bend you over on this one so I suggest going to a site like autozone.com that offers free repair info and procedures, you might be able to use alldata at you're local library but if your not a mechanic it might be a little to technical or confusing but by far the best diagnostic resource available. I would explain the procedure for replacing the speedometer sensor but you would be much better off with pictures so you know what your looking at, hope it helps
I'm no mechanic, all I can do is turn the key and change tires. I would recommend you speak with your local auto parts store they may be able to give you that advice. Or perhaps purchase the Chilton repair manual for your make and model at your local auto parts store.