First check if you already have SSH keys or not with the following command:
If you don’t have your own SSH keys, you can create them using the following process:
Open a terminal run the following command at first:
There will be output something like below and follow the onscreen instruction and press the enter key and go with the default choice. You might have a password for your SSH key.
Generating public/private rsa key pair.
Enter file in which to save the key (/user_home/.ssh/id_rsa):
Copy the content of your public key from the file cat ~/.ssh/id_rsa.pub . You need to paste the content of your public key by logging in to your GitLab account, going to User Settings, and clicking on SSH keys in the left sidebar. Then you need to paste the public key there and hit the Add key button. Now, you can easily push your code changes to the Gitlab account.