Collections error 400 but sending client id

Thanks for your reply.
Looks like the problem is when i send the php string. I tried using terminal and curl cmd’s and it worked.
I just dont know whats the query string format to use in this case:

https://api.twitch.tv/kraken/collections/myIbIFkZphQSbQ/items&client_id=xxxxxxxxxxxxxxxxx
ou
https://api.twitch.tv/kraken/collections/myIbIFkZphQSbQ/items?client_id=xxxxxxxxxxxxxxxxx

Is there any PHP docs or examples?

Thanks in advanced!