Hello. I'm wondering something-how does one add a signature thing to their posts? Also, I am wondering how one would get some of those picture-things on their signatures that say stuff like "TI-Nspire CX CAS User", etc. Please help, I am a complete and utter Omnimaga noob.

Iirc you need at least one post to have an avatar/sig/etc, so that shouldn't be a problem.
E: you need the 1000 posts to have a custom title.

You click on Profile in the bar thingy at the top of the page (Home, News, etc) and then Forum Profile Information on the left.

For adding the images, you use the [img][/img] bbcode tag with the URL of the image inside, or if you want put the whole thing in a Url itself.
So this...
[url=http://www.omnimaga.org][img]https://www.omnimaga.org/Themes/omnimaga4/images/omnimagabanner2010.png[/img][/url]
does this..

Also if you use a signature, make sure it'S not too big either. Normally we're tolerant on that matter, but overly large sigs (both in KB and pixels) can be annoying.

Also if you use a signature, make sure it'S not too big either. Normally we're tolerant on that matter, but overly large sigs (both in KB and pixels) can be annoying.

You can always put them in spoilers if the signature gets too large.
Just add the [spoiler] tag and you can also name the spoiler too
When finished just add [/spoiler]

[spoiler=This is a Custom Spoiler] Well hello everyone, Hope you peeked in this spoiler. If you are interested, you can click the links in my sig (most of them are dead projects anyway, soon to be revived) [/spoiler]looks like this:

You get used to typing in BBCode manually around here, as it is quicker typing in the quick reply box at the bottom of the page than going into full reply mode where the buttons for BBCode are available.
It's quite simple actually

[b] [/b] turns things bold
[i] [/i] italics

From what Darl181 said:
[url=http://www.omnimaga.org][img]http://www.omnimaga.org/Themes/omnimaga4/images/omnimagabanner2010.png[/img][/url]
[url=http://...] at the beginning is the url
whatever is in between [url=http://...] and [/url] is the text to be displayed for the link, or an image such as [img]http://myimage.png[/img]

There's a guide somewhere: http://www.omnimaga.org/index.php?action=help;page=post

Also welcome to Omnimaga! I know you've been here a few weeks but head on over to the Introduce Yourself Board http://www.omnimaga.org/index.php?board=10.0 and introduce yourself!

If you master Photoshop or GIMP, you can do pretty wicked effects, like diagonal lines, gradients, the oval-shaped shadow at the top or even shadow on the fonts. And it's just the tip of the iceberg.

Obviously.

Actually I got this bar on DeviantArt.

Is it just me, or does it bug anyone else how the rainbow jumps around like that instead of scrolling?

It does both, it just depends of your point of view. With enough concentration, I think you can make it scroll the other way.