How do I add a frée channel when I try it asks for pin when I put pin in it says wrong pin

If you log into your account at https://my.roku.com you can create or reset a Roku PIN value. You can then choose when the PIN is to be required, such as before it will allow any subscription or purchase to be made on your account, or a new channel is added.

Some channels may also have their own PINs.  You likely would have to manage these by logging into your account on the channel's website.