How to do the behaviour like prompt line in zmud

I want send the userid and password when trigger is on. I choose the option "send to world(immediate)" when I create the trigger. But I still need to input the return to server. Why? How can I do for it? Thx.

Triggers only fire at the end of a line. You are better off putting the username and password into the box to be sent upon connecting (see world configuration -> Connecting).