Everything that Arron said. I personally find the fact that nobody cares about your age very reassuring.
One thing I'd look out for though (I've been pulled up on this before). If you are a high school student - you aren't a software engineer, in the strictest sense of the word. Yes you might ... "engineer software", but you aren't really qualified to use that as a title.
I know engineers who are very picky about this, and who detest anything that doesn't warrant you a place in the Engineering Society, using the "engineer" title. (i.e. sound engineer, video engineer etc).
If you remove the "high school student" thing, (which you absolutely should), and leave the "software engineer" thing, you might give people the wrong idea, and IF (on the off chance) that they ask to see qualifications, or even just ask you about it, you'll be in a tough place. Better to just put what you do "website development, graphic design" or whatever service it is you are offering, than pretend to be qualified in the area.
To be completely honest, most people don't even care about qualifications any more. A good portfolio goes much further (in many cases - not all), than a resume full of college or Uni degrees.
I'm not doubting your ability, or saying you aren't better than people who *have* gone and done degrees, but it's just polite to 1) allow people who have done degrees to be the ones able to use those titles or ... descriptions and 2) not confuse people as to what you actually are.
Hope I've made the point as clear and simple as possible. I'd actually love to hear what some other guys think about it, and whether you agree/disagree with what I've said and why.