How to take fullscreen screenshots on Linux with LXDE?

[Your Computer]

I don't think LXDE brings its own screenshot program. Not sure which distro you're using, but there are plenty of screenshot programs for Linux.

If you're trying to take a screenshot using the game's built-in feature (shortcut being F8), the screenshot will be "dumped" where the game is installed in. If you're not, then what you're asking isn't related to the game at all and shouldn't be posted in this section.