How to use SquidMan and force apps to go through it?

I have installed SquidMan and gave it the following details:

General tab:

HTTP Port: 8080

Parent tab:

Hostname/IP: 10.18.1.3 (work proxy)
Port: 8080 (work port)

Username: myUserName
Password: myPassword

Then I clicked save and Status: Squid is running

Now, How can I force my installed applications to use it for all HTTP and HTTPS connections?