If you want to take your ferret for a walk, you will need a collar, harness and leash. You must also understand your ferret's need to have a safe place to hide if scared, and a chance to explore without being tugged or dragged along. A ferret collar can be as simple as a cat collar that is made to fit the ferret; it should just slide off her neck if the ferret gets her head into a place too small. Since this is very likely with most ferrets, adjust the collar so you can slide it on over the ferret's head to make sure it will come off if it has to. A bell on the collar and an ID tag will keep the ferret entertained when you first put on the collar. Let her get used to the collar before moving on to the next step.
To learn more, read Taking Your Ferret For a Hazard Free Walk