How to set the production.json

[tiaoyu]

I set up a turn server
and I have a user name, a password or a key
and what can I do in the production.json？
because

"turnservers": [
{
"urls": ["turn:www.tiaoyuyu.com:3478"],
"secret": "turnserversharedsecret",
"expiry": 86400
}
]

in “production.json”
My doubt is what to fill in “secret”
is : "username:password"?
or: "username:key"?
or something else?

Forgive my English is very poor
hope some one can help me.
thanks very much
谢谢！