Most companies want to hire people with one or more of these skills. The more skills you possess, the better it is to land a good paying job. There are lots of people who want to improve their skills for a better paying job and your training will offer that to them. If you offer a variety of classes, you will have more clientele. A person who takes the Microsoft Word class may come back for the Microsoft Excel class.
Some people find it easier to take a course than to learn something from a textbook.
When you are looking for a course, look for something short and simple. Look for courses that last five or ten evenings. Self-Instruction is another method of learning. If you are good at perception and understanding things easily, then you can instruct yourself. You can purchase books on the particular subject you would like to improve and go through the book on your own.