What do I need to do to get my Cox boat trailer titled in Va?

I bought a 70's model Cox boat trailer from a lady in Tennessee and I live in Virginia. She wrote me out a bill of sale for the trailer and told me that she didn't have a registration for the trailer because Tennessee doesn't require owners to register or tag boat trailers. Her husband owned the trailer and he died and she really didn't know what all I would have to do to have it titled in va but told me to find out and she would do whatever she needed to do to help me when i found out what I needed. I can see where the trailer had a sticker "I suppose the sticker with the vin# and information" that must have fell off because it is a pretty old trailer. What do I need to do in Va to get an untitled TN boat trailer without a previous registration and a readable Vin# titled in my name. Repeat: I do have a bill of sale. Thanx