I installed Turtoise Git and has been unable to pull:

From https://gitlab.com/website.com/restapi
= [up to date]      master     -> origin/master
Updating dad62f8..d807062
error: Your local changes to the following files would be overwritten by merge:
Please commit your changes or stash them before you merge.

git did not exit cleanly (exit code 1) (4391 ms @ 16/07/2018 10.08.12)

I should create git stash first but do not undetstand how to?

I already read https://git-scm.com/docs/git-stash

Can anyone guide me how to create git stash?

I think you need to spend a little time learning git before you dive in and start using it. Git can be a cruel mistress.

To stash your work run git stash. It says that in the doc you "read".

In short, don't pull when your repo has uncommitted changes.