You start off selecting your powers, and then you make your character. Don't forget, you can set your powers, come up with a look, and then go back and change your mind on your powers before finally finishing your hero.
The steps are, pick a framework, head, body, costume (costume is done in a series of tabs), and finally Name/Bio.
Within those steps you can go back and forward with it them without losing data, and if you want to avoid risk you can always save your look.
Also, you can do what I do, and go in, pick any power, and come up with a hero, save them, then just make them later when you've decided what end-builder + main attack to pick.
PS, on a note about sharing your costumes, you'd need to email the jpg, or zip it when you upload it somewhere, so that the meta-data is not erased (it won't work with many online services, since they convert jpg to their own web friendly version).
So if anyone can point me to an image sharing site that won't lose the meta data, I'd appreciate it.