Okay, okay. First, let me mention that the book is about forty miles away from me right now; this is from memory, so it will be a little vague.
The rules are designed to drop into d20 Modern. Super Hero is an advanced class. It's even easier to get into than most advanced classes (the only pre-req is having at least one Action Point) and has a full 20 levels of advancement. (Even though the most you could really use is 19, unless you're in an Epic Modern game.) The class has customizable saves, and (IIRC) a middling BAB advancement.
Powers have ranks just like skills, and as you gain more ranks in a power, the power either develops extra advantages or loses disadvantages. In addition, each power has a "GO! Power" application, where you spend an Action Point and get an extra benefit temporarily.
When a character picks up the Super Hero class, they also select an origin (Altered Human is the only one listed in the preview; presumably Atomic City will have more) which gives you an ECL (3 for Altered Human) and a variable number of powers (AH get one at 3 ranks, one at two, and one at one IIRC.) each level of Super Hero gives you a Super Feat, which can get you more ranks of a power, extra tricks to use with existing powers, and occasionally a new power.
And that's basically it. It isn't nearly as flexible as something like M&M; the resulting characters also won't be as "super" - I wouldn't attempt the Justice League with these rules, but I think they'd handle the X-Men (especially Movie X-Men) quite nicely. However, it balances nicely with d20 Modern. I think the best use for the rules is to cover d20 Modern characters with extra abilities that aren't handled by the main rules - if I were doing a League of Extraordinary Gentlemen game, for instance, I'd use the Fiery Dragon rules for the Invisible Man and Mr. Hyde.
Of special interest to you - the Fiery Dragon rules use OGC from Four Colors to fantasy; I don't have 4CTF, so I don't know what.