To set your password, add the following line to your ~/.bashrc (or whatever file runs when you start your terminal):
export GIT_ASKPASS="<password goes here>"
What this does is set the environment variable GIT_ASKPASS to your password. When git looks for a password, it will see that you have the GIT_ASKPASS set, so it will not prompt you.
Do not do what @thepiercingarrow has suggested and put your password in plain text in .bashrc. This is a terrible idea. I might look convenient but this is how accounts get compromised. Follow the link from @ershad.ahmad, an SSH key pair is easy to set up and more convenient in the long run.