I am having a bit of a issue finding the way of how to change the wallpaper for Linux Mint 11 log in screen.
Do you guys know how to do this?
Linux Mint, I know is based off Ubuntu, so I'll give you the Ubuntu answer to the question.
Under the System menu (which I know, Mint doesn't have but it should have it as a sub menu, if not, look for the rest of what I'm telling you here), look at the Administration submenu, then under Login Screen. Under that, I believe believe you can change it. If not, you'll have to look in the repos for something called 'Startup Manager' and install that, which should allow for you to change your login screen.
Failing that.... this solution will work, linked here. I don't know any soloution outside this... Long explanation shorted: Change theme, modify theme, or you may download a theme that fits you well... hope this was helpful
Alternatively, if you don't want to install the ubuntu tweak package, you can change the login background from the command line like so:
First change the default background, since gdm is already configured to use it as the login background.
Then clear out the gdm cache to force it to regenerate its background image.
And viola! The next time you have to login or unlock your screen, gdm should display the new background.