AE stands for Alter Ego.  Bascially, the characters are based off of a part of yourself.  For example my AE, Wendy, is based off of my dissasociated philisophical side.  The AEs do develop within themsleves, and exist as a form of OC that can stand alone as a good character.  They will talk in a different style than the CBer, either itallics, bold, or bold itallics.  They can range the spectrum from bubbly to broodingly edgy.  CBers will also sometimes ship their AEs with eachother. 

If you work fast, you can have one in time for the new AE ball!   You can look around and find some examples of AE introductions if you need a reference base.

I hope I was at least a little helpful.  More experienced CBers, if I got anyhting wrong please do not hesitate to call me out!

AEs are like characters of yours that post in your posts/will occasionally make their own. They chat, interact, and fall in love with each other. 

The first AEs were originally modeled after aspects of their creator's personality that didn't come out often (hence the name Alter Ego). I'd say that maybe half of the AEs we have nowadays are like that. Also, random note, this type of AE is my favorite. 

Other AEs are just interesting characters that their creators make up. Some are crosses of both types. An example of this is if you take some aspects of your personality and give them to a character. 

AEs talk in your comments like this:

Hi! This is an example of how AEs talk in your comments. 

See how the AE talked in bold (you've probably noticed this in AE threads already)? AEs talk in the fonts we have on the Chatterbox (ex. Bold or italics), which limits how many AEs you can have. Technically you can only have three AEs because that's the number of fonts we have (bold, italics, bolditalics). Reusing fonts in AEs can get really messy. For example, if you had two AEs that talked in bold.

It's great that you desire to make one. While other people have had  their own characters from stories or other writing websites that they make their AEs, and have been able to release both of them at the same time, starting with one AE is a better idea (at least for me). That way you can spend time developing just the one AE.

But it might not be that way for you. You might be able to develop multiple AEs at once... but I would personally recommend starting with one. Hey, I'm biased. 

I hope this helped!