Feeling a calling to go back to work

So I haven’t had a job for many years. My last job was for a car insurance company. I left that job to start a family. Now a mom of 3 boys. 6,3,2 ages. I am having a strong calling to work within a school. Every time I drop my oldest son off at school I want to stay and help out in any shape or form. Only issue is I’m pretty far behind on computer programs like spread sheet, Microsoft word, and some other programs. I really want to work with elementary students or in a office of my sons school. Do you have any advice you could possibly share? I really would appreciate any feedback. Thanks :)