These are the basics that you should use all the time:
- CTRL+C: Copy
- CTRL+X: Cut
- CTRL+V: Paste
- CTRL+Z: Undo
Copy - picks up whatever you highlighted and stores it on a clipboard so you can paste it in a different place or program. For example, you could copy some text from a website and paste it into a Word document (think C=copy)
Paste - of course, puts whatever is on your clipboard into the location you select (think V=points down to where you want to put stuff).
Cut - Copies AND REMOVES whatever you select and puts it on a clipboard so you can paste it (think X=scissors).
Undo - undoes the last thing you did (think Z=zzzzzz oops, I fell asleep). You can Undo multiple times to keep stepping backwards through the actions you want to remove. This even works when writing emails - helpful because there's no obvious undo command.
I can't tell you how many times I use CTRL+Z!
Of course there are many more keyboard shortcuts. Here are official lists of shortcuts for Windows and Macs.
Why don't you try learning one per month?