In a word, no. As in any other aspect of teaching, the more prepared you are, the better. However, the basics of what you need to know are covered during the short but informative orientation you will be given if you decide to teach in the computer classroom. A basic familiarity with the technology you'll be using will be helpful, and you will want to spend sometime "playing" with that technology before you begin using it in the classroom, but relax: you will receive a lot of support on the technological aspects of the computer classroom. No one expects you to be a computer programmer or even to be especially computer literate.