starting from nothing and have no idea where to start to make a simple bar graph ggplot2

We don't have your Terpenedata.I don't think we need all of it, but 'some' of it would be useful. Maybe pick 2 of your Compound and share just the data for those.
FAQ: How to do a minimal reproducible example ( reprex ) for beginners - meta / Guides & FAQs - RStudio Community