Thank you for the question.
You can start with MS Office Packages which includes most of the productive tools in work-life(They may seem super easy but need more attention than we initially thought to be pro.). Moreover, you can follow the following process to learn.
1. Find Out what you need to learn.
2. Start with the basics of the topic.
3. Try to familiarize yourself with an understanding of the basics.
4. Take a free online course that you figure out.
5. Try to apply it in real life to get hands-on experience.