How to change proxy?

I made this post to help the ones who don't know how to configurate a proxy.
Attention the images are in portuguese and the tutorial is just for Mozilla Firefox.

Just follow the steps:

1st:

2nd

3rd:

4th:

5th:

6th:

Follow the eg. where "proxy is wrote".

So I hope this helps besides it's in portuguese (as you may know i'm portuguese). But anyway follow the images and you can do it.