A feral wolf that can talk; good work, you have yourself a fursona.
It's not very complicated.
Anything you want to add now is just icing on the cake; fur color, markings, piercings, personality, whatever you want to add or not add. What most people do is just add their own personality into their fursonas, but it can be whatever you want, but to let other people know how your fursona looks you'll have to either write up a description, draw a picture, or get someone else to draw it for you.
Truth be told, you don't even really need a fursona if you don't want, you can enjoy furry things without all that.
But, yeah, not much to it.
Anything in particular you want to know?