Http hear request into Keystone

Question

I want to take token from keystone and examine them by getting a lot of them.

I already got one token by using REST API as:

Now I want to get a lot of token so I using Webscarab application as:

but I don't know which header I need to provide. I try to put:

Content-Type: application/json
id_username: (myusername)
id_password: (mypassword)

but failed.

Anyone know that, please help me.