dont know how to..

Clean up her back legs she is just beginning to lose her winter coat so she is still fuzzy wazzy the hair is extra ruff and stained and being white I don't kave a clue

Welcome to the forum, speidel! Don't worry too much about the 'extra' hair right now - nature has a way of making sure it will all shed exactly when your horse needs it to! Just continue brushing and also a rubber curry feels soooo good to your horse right now as well. There's always a reason for the extra hair to stay for a while, and nature knows better than us. Everything in it's own good time.... :)

Until it gets warm enough to give a good bath, I would suggest one of those slick and easy grooming blocks- if you are gentle you can use them on legs with great success! I don't recommend using a curry comb (unless its a really "scooshy soft" one on legs, because there isn't much protection (muscle/fat) on the horses legs, just bone and tendons/ligaments!

If you are trying to get ready for a show, clipping her legs will make them much easier to clean.

Once it is warm enough for a bath, there are tons of whitening shampoos that you can rub on, leave in, and then rinse off for sparkling white legs!

Best of luck!