One of the best tutorials on plotting in R using the ggplot2 package is Rick Scavetta’s datacamp tutorial. The first chapter is free and covers a lot of excellent material about ggplot2. I strongly recommend you go through the first introduction chapter of this tutorial.
As a helpful guide, take a look at the RStudio cheatsheet for ggplot2.
ggplot2ggplot2 Cheatsheetggplot2 reference guideggplot2ggplot2 visualizations