This all depends - if you have no clue as on where to start, and you want it to look professional, ask/pay someone who does know to do it for you. I'm not meaning to sound harsh, but if you're seeking something professional-looking, it's best to leave it to someone with experience *or* keep it really, really simple.

If you don't mind learning from scratch, and don't mind what you end up with, then there are loads of HTML tutorials out there - a quick search on Google should give you loads of beginners' guides. It may seem daunting learning HTML, but it's worth it - you get more control than just using a web editing package.

Best tips - simple as possible, lay it out as it would look on a single page, consistent colours and fonts, no clip art and no blinking/animated text or images!