Unless you're out shooting points for surveying as opakapaka mentioned, it's completely a desk job.
You might check into taking a couple cadd classes at one of the community colleges and then once you feel you're getting a good grasp at things, sign on with a temp agency that can place you in cadd jobs according to your skill set. There's nothing like hands on learning and for a lot of these jobs, the required skill set is very minimal as the need for extra cadd help usually arises on large projects requiring hundreds of design drawings to be annotated. The couple engineering firms I've worked for quite often went to temp agencies to bring on extra cadd help when the need arose. And the cadd technicians that showed up had skills anywhere from 'almost can do 3D' to 'they probably fibbed on their resume about knowing cadd'. These temp gigs are excellent experience to put on a resume and may even lead to a permanent position.
Cadd is taking the drafting of yesteryear and putting it into computers and as such, you need to also be computer literate. You have to know your way around a computer, understand file extensions, folder structures, that sort of stuff.
Hope this helps.