Place the contents of the gamedata folder within the gamedata folder of your KSP install.

Don't even look at the Extras folder unless you know how to read Module Manager files. Just don't do it. They're all unsupported.

WARNING! If you've downloaded from Spacedock note that the included B9PartSwitch is for KSP 1.8 ONLY. If you are using a version of KSP older than KSP1.8 please use B9PartSwitch v2.11.1 https://github.com/blowfishpro/B9PartSwitch/releases/tag/v2.11.1
