How do i get Proxy Address?

A open wifi,connection is http. connecting it requires a username and password but it can be bypass using the proxy address, few days ago one of my friend gave me a proxy like 10.10.3.2 and port was 80 . After setting it, don't need any username and password and connect multiple users. I have also username and password of account but "one login at a time ". I need proxy to login multiple users at a one. Can anyone help how to find proxy address using wireshark? Any help would be appreciated ^_^ . Thanks in advance.