Matching the Basics
Start with the basics: literal characters, character classes, and repetition.
Literal Characters: Match a character exactly once. Like, don't even try to be fancy, just match the thing.
hello
Character Classes: Match a character from a set. Like, it's not that hard, but you might need a few tries.
\d
Repetition: Match one or more of the preceding element. Like, don't even get your hopes up, you'll probably still get it.
\d+