You have a new project, or opened a project not under version control. First thing is to fix that by making a local repository.
You can use your mouse to go to the
VCS -> Enable Version Control Integration
menu item. But you can also do this from the keyboard, to get to the same
dialog, without leaving the keyboard.
Find Action (
Shift-Cmd-A macOS) and speed
en ve co (meaning,
Enable Version Control). It should be the
first matching item. Press
Enter to invoke it.
The dialog that pops up wants a selection of which VCS system to use. If it
is Git, type
g and the dropdown will select Git. Select
Ok to perform
This action adds a VCS root in your
Settings/Preferences -> Version Control preference. Later, when you want
a remote, you can use, for example,
Share Project on GitHub.