Just a quick walkthrough on installing SquidGuard and getting it up and running.
1. Install squid and SquidGuard packages from package manager
2. After installation, go to Squid Proxy Server under services
3. Go to the Local Cache and scroll down to the Squid Hard Disk Cache Size area and click the orange "Clear Disk Cache NOW" option
4. Go back to the General tab and scroll down to the Transparent HTTP Proxy area and check the box for Transparent HTTP Proxy "Enable transparent mode to forward all requests for destination port 80 to the proxy server."
5. Scroll to the bottom of the page and save
6. Go to SquidGuard Proxy Filter under services
7. Scroll down to Blacklist options and check box to enable Blacklist
8. Add http://www.shallalist.de/Downloads/shallalist.tar.gz into Blacklist URL
10. Scroll up and go to the Blacklist tab
11. Click the green Download option and wait for download to complete
12. Go to Common ACL tab
13. Click on Target Rules List + sign
14. Scroll down and change Default access [all] to "allow"
15. Deny Porn and Spyware categories (and any other categories you wish to block)
16. Scroll down and save
17. Go back to General settings tab and hit green "Apply" button
18. Go back to Squid Proxy Server under Services tab
19. Check box to enable Squid Proxy and save
20. Go back to Squidguard Proxy Filter
21. Check box to enable and save
22. White box should say "STARTED"