popup window with return value

i want to implement a facility like :

there is a form & there is a text box for name & button for browse the user list.

when browse button is clicked, it will open a new popup window containing the user list.
now when end user clicks on a name/picture of any user in userlist....this name should be placed in name textfield.

uptill now, i can only do is to open a popup window with userlist,
Now please help me to get return value from popup window & place it in name field...

thanks in advance...