How do I install plugins?

so i downloaded these free scrips now what do i do to have them show up in sketch up?

Go to the SketchUp menu (left of File), click on Preferences>Extensions. Click on the Install Extension button, navigate to the file, select it, click Open and then choose any positive answers at the prompts.

Thanks Dave your the best

See this Help article…

Installing Ruby Plugins (Extensions) — SketchUp Help

I have SU Pro, on a Mac running Sierra OS. Under SketchUp > Preferences I do not see Extensions.
Any Help would be very welcome.
Thanks

For 2017, go to Window > Extension Manager

CD

Thank you.

I wish SketchUp allowed people to just double click RBZ files to install them.