If you have the computer skills necessary to find distance learning courses online, select one, register for the program, and pay for it, then you almost certainly have the skill necessary to complete the courses. There are, of course, exceptions.
Word processing and using e-mail are pre-requisites for online learning. They are the mainstays of interacting with your instructor and classmates. There may also be a "chat" room or other forum for informal communication. These are fairly self-explanatory and can be learned with minimal experimentation. It is likely that someone computer-literate enough to get into the course is already familiar with them.
Spreadsheets and slide show presentations are a bit trickier, but the basics are easy to learn. You can start by taking courses or tutorials in the necessary programs in order to produce a polished product for your courses.
Should you choose a program on a more technical subject - especially one involving networks or other computer support, you would of course need to know a great deal more. Such courses would have the knowledge needed to pass as pre-requisites, so you would not qualify to take a course based in specialized software or other training.
You should, however, look at advanced courses you hope to take later. You can use the listed fundamentals to help you decide which entry-level classes to choose from an often dauntingly diverse catalog. They will also help you to plan your progress through a program to ensure that you end up with the experience you need to get the job you started your training for in the first place.
Look at the requirements and course description for the distance learning program before you sign up. You should be able to discover which programs you need to be familiar with so that you can prepare yourself ahead of time. Don't be intimidated by new software. Learning to use it for a class will only help you when you need it in your new, improved job!