How can I check how often I have used my new MacBook?

In the Utilities folder in Applications is the console tool. It serves the same purpose as Event Viewer on windows and you’ll have the same needle in the haystack experience on macOS as someone is in Event Viewer the first time they launch either.

Since macOS is Unix, you might get all the details you need from the command-line.

last

That command reads the wtmp file which you can read up about online here and elsewhere for what a console log in is. The pmset command is also useful if you like to look for sleep/wake events which aren’t the same as logging in.

Welcome to mac and happy learning!