I understand that there are already a few guides on changing proxies in this forum, however I feel that some of the guides may be rather troublesome especially when you are trying to create multiple accounts on different ip addresses.
That's why I'm recommending a few proxy changing programmes that are safe and free of charge.
Personally, i have tried each of these programmes in the past to bypass school block sites and they are rather reliable >.<
Advantages: (Each of these programmes have an arsenal of its on list of fast and reliable proxy servers which will allow you to alter your ip addresses many times with a single click of a button)
Disadvantages: (You will have to download it/ May take some time to figure out how it works)
1) Hot spot shield (Free with ads)
http://www.hotspotshield.com/en
2) Tor browser bundle (Free)
https://www.torproje...browser.html.en
3) HIde ip easy (This is a paid application/ however there's a trial version available)
http://www.easy-hideip.com/
I have a cracked version of hide-ip easy but I am not sure if im allowed to post a download link here...
So before you use the programme, you can check your ip address here,
http://www.whatismyip.com/
After using any of the programmes above, to be safe, check that your ip has changed to a different one,
http://www.whatismyip.com/
To be safe, while using the programme, you should also clear the cookies on your browsers just in case.
Hope this helps - My first mini guide =)