How to run recorder if a website is behind proxy?

Hi,

In recorder i gave outgoing proxy details and in fire fox i set up manual configuration as same proxy settings. Then getting proxy error. If i give 127.0.0.1 as host name i am able to record but getting a pop up to enter user name and password for my application. So could you please help with that… I am new to Gatling so no idea of how to do this?