ssh gitlab

1) Open Git Bash (Download and Install Git Bash; You can use any *nix based command prompt).

2) Type

 cd ~/.ssh 
This will take you to the root directory for Git (Likely C:\Users[YOUR-USER-NAME].ssh\ on Windows).

3) In the .ssh folder you should find these two files: id_rsa and id_rsa.pub. These files tell the computer how to communicate with GitHub, BitBucket, or any other Git based service.

Those files were obviously missing from my computer so I had to create them.

 ssh-keygen -t rsa -C "[email protected]" 
Type this to create those two files
Once you entered that command, you will get a few more questions:

Enter file in which to save the key (/home/demo/.ssh/id_rsa):
You can press enter here, saving the file to the user home (in this case, my example user is called demo).
Then this will be shown:

Enter passphrase (empty for no passphrase):
The only downside, of course, to having a passphrase, is then having to type it in each time you use the key pair. I suggest you to use a passphrase though, due to security concerns.
In the end, the entire process looks like this:

Enter file in which to save the key (/home/demo/.ssh/id_rsa): 
Enter passphrase (empty for no passphrase): 
Enter same passphrase again: 
Your identification has been saved in /home/demo/.ssh/id_rsa.
Your public key has been saved in /home/demo/.ssh/id_rsa.pub.
The key fingerprint is:
4a:dd:0a:c6:35:4e:3f:ed:27:38:8c:74:44:4d:93:67 demo@a
The key's randomart image is:
+--[ RSA 2048]----+
|          .oo.   |
|         .  o.E  |
|        + .  o   |
|     . = = .     |
|      = S = .    |
|     o + = +     |
|      . o + o .  |
|           . o   |
|                 |
+-----------------+
The public key is now located in /home/demo/.ssh/id_rsa.pub. The private key (identification) is now located in /home/demo/.ssh/id_rsa.

4) Copying the public key to GitLab

Go and open the id_rsa.pub file (you can use any text editor you want).
Copy the entire content of that file and then open https://gitlab.com/profile/keys.

How GitLab SSH Keys page looks

Paste the content you copied from id_rsa.pub in the Key input (don't add extra spaces or characters).

Give your key a descriptive name and then Add the key.

5) Try to git clone or git push.

I really hope this will help someone because this article is what I needed last week when I couldn't put things together and all seemed to be way harder than it actually is.