It will be best to contact your local college to see what courses you need to take to become a computer technician.
For example there are many community (2 year) colleges that offer Associate's Degrees for Computer Technician and etc.
Here is a listing of community colleges in the US you can contact to get more information:
http://www.utexas.edu/world/comcol/state/
Here are some resources you might find helpful for preparing yourself for a career as a Computer Technician...
You can also use a search engine like Google.com to find many free tutorials, ebooks, forums and other information for PC Repair, Computer Networking and etc…
Professormesser.com has many good video tutorials for PC Repair and Computer Networking:
http://www.professormesser.com/2008/03/15/professor-messers-free-comptia-a-certification-training-course
Mr. Messer is a computer repair expert and you can contact at the above website to get advice on how to become a computer repair technician
There are many forums for Computer Repair and etc...you can ask them for any advice and information
http://www.google.com/search?hl=en&q=Computer+Repair++forum&aq=f&aqi=g10&aql=&oq=
At www.fonerbooks.com the author Morris Rosenthal has written some books that contain flowcharts for troubleshooting computers
Here is a free sample of his book
http://www.fonerbooks.com/computer_repair_with_diagnostic_flowcharts.pdf
You may find his books at Amazon.com or at your local library or store
The website also has information on how to start your own computer business
You can contact Mr. Rosenthal at the above website to see if he could give you some advice on how to start up your own computer business
Various Computer Networking tutorials:
www.networktutorials.info/index.html
Top-Windows-Tutorials is a good website for learning about Windows XP, Vista and Windows 7; how to protect your computer with antivirus and firewall programs; backing up your files and data, and etc.
http://www.top-windows-tutorials.com/Backup-tutorial.html
You can go to your local library or store or an online store like Amazon.com to find many books, DVDs, and etc. for repairing, maintaining, troubleshooting computers and networks…
You can also save a lot of money by buying the used copies of the book.
http://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Dstripbooks&field-keywords=Computer+Repair
http://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Dstripbooks&field-keywords=A%2B
Basic Electronics by Bernard Grob is considered the best introductory book for learning electronics
http://www.amazon.com/Basic-Electronics-Bernard-Grob/dp/0070249288
YouTube also has many tutorials for fixing and maintaining computers, setting up and maintaining computer networks, Windows XP, and almost anything else you want to learn:
http://www.youtube.com/results?search_query=Computer+how+to&search_type=&aq=f
http://www.youtube.com/results?search_query=Computer+Troubleshoot&search_type=&aq=f
Good luck and I hope you will find this to be useful!