As a blanket DIY approach I would suggest getting a few examples of your work together, and using sites such as Craigslist.org and Backpage.com to scour through the available writing positions that specifically mention freelance technical writing.

Having no experience in this particular field, I think that you should avoid websites and services that serve up writing opportunities for career-minded writers. This isn’t to say that you cannot make a career out of technical writing services without experience, it’s just that I think you would have more success finding a small company or individual looking for technical writing services as opposed to a large or established company.

Large companies tend to look at resumes, training and such whereas individuals and small businesses tend to look at your writing ability and are more willing to give you a shot based on your writing samples alone.