Editing facebook contacts

What exactly do you mean by "edit" FB contacts? Do you mean in Contacts? Most conversations about that are about how to link views of your contacts so you don't have double/triple contact cards for each contact e.g. a FB one, a Gmail one, a Skype one, a Twitter one etc (options will depend on how many accounts you are signed up to).

If this is what you mean then if you open a contact in "people" you should see a little icon on the screen that looks like a "link" or it maybe in your menu options for that contact - press on icon and it will give you all the different account sources about that person and give you the option to manage links.