So I would like to have a few questions answered to some stuff about the signature. I would have asked my mentor but I still haven't got one and my curiousity is big so... 

1) I noticed a lot of different graphics (aside the signature) which people have. After searching more I've found out how some of them are called but I still have some questions about them. 
First are the "bumpers". I would like to know what are exactly those, when and why are they made, can I create my own bumpers, how many can I have in the signature section? I already got 2 from the GC 4th anniversary but they are waaaaay more I saw around the forum.
Same questions for sprites, stamps and those things you click and they level up. 
I searched for a topic but I couldn't find it. I am not sure where to look T_T

2) The "random" signature function? I noticed some members have multiple signatures and they seem to "auto-change" it whenever I reload a new page. How do you do that? :O

3) Oh and where should I post my graphics and stuff like that?

1) Bumpers are the 100x100 images typically on each side of someone's signature (I see you have two of them right now!) They are usually handed out during forum events (like the anniversary), as game/contest prizes or to show off your membership in some of our clubs (you can find a list of them here). You can also make your own bumpers!

As for how many of each type of graphic you can have in your signature, please read this.

More helpful threads:
Stamp Information
Adoptables (the things you click to level up)
Sprite Shop

And finally, since the last two have to be bought using GC points, here is the thread explaining how to get points and spend them!

2) Signature randomizer sites: the most commonly used are signavatar.com and sig.grumpybumpers.com. You just plug all the image URLs there and they will give you one main URL to put on your signature and they will be randomized automatically.

3) The Artists section would be best to show off your graphics

Thanks a bunch, Mercury!  Everything is clear now! ^^