Hello to you and welcome to the world of technical communications. One of the ways you can get started in the freelance tech writing business is to do some contract work. I'm not sure where you live, but many places have contract agencies that hire contract writers to do projects for their clients. They generally hire people for short or long-term contracts depending on their clients' needs. They pay you an hourly rate on either a 1099 or corp-to-corp (if you are incorporated). You will work at either the client's location or from your own office, again depending on what the client wants. To get started in the business, I would recommend you find and contact all the contracting agencies in your area. For starters, try an agency called Proedit (proedit.com). This agency is located in Georgia, but they contract for clients all over the US. You can submit a resume online and apply for their jobs in any part of the country. And they are a very professional and reputable agency. Another agency you can register with is Matrix Resources (mymatrix jobs.com). Again, they recruit for jobs all over the US.
Get as much training and practice as you can with all the writers' software tools: Word, Excel, Frameworker, web site tools, etc. Join the Society for Technical Communication (STC) and get involved in their networking meetings. Look for an STC chapter in your local area. Find all networking organizations in your area involved with technical businesses: computers, engineering, medical technology (your choices will depend on your areas of interest.)