how to install notepad++

Go to the official downloads section at https://notepad-plus-plus.org/downloads/, download the installer, run the installer

what is lint

“Lint” is the fuzzy stuff that comes off clothes in the dryer, and has nothing to do with Notepad++

A “lint” tool (aka, “linter”)" is a tool that checks the syntax of source code for correctness, bugs, and stylistic errors. If you are typing your code in Notepad++, there are ways to pass that code through an external program like a linter, but there isn’t a linter built into Notepad++.

I am not sure how the “lint” subject of your post has anything to do with Notepad++, or why you asked that part in conjunction with “how to install notepad++”.

Further discussion on linters does not belong in this forum, unless it is focused on Notepad++ (and I’m doubtful that it would be).