In order to have your signature show up, go to "Profile" then "Preferences". Look for "Always attach my signature". Then save.
If that does not work, when you make a post, an option to "attach signature" should be visible.
Spoiling Large Pictures/Etc
To spoiler a large picture or anything else, on your posting box...
Look at the right hand side, you'll see "Others", then choose "Spoiler".
If you want your Username changed, simply PM me on here. I will change it asap and if it's appropriate.
Upload Pictures From Laptop/Desktop/etc
On the right-hand side of the buttons, you will see an image of a floppy disk. Click on it. Upload a picture. It will give you a link for the picture. Copy & Pasta the link with the IMG code. *use spoiler if its very large*
Easier than going to imageshack or some crap.