R is free and open-source and can be run on Athena or downloaded to your personal computer.
Download R Studio, a guide to use with R.
A variety of tutorials, learning modules, recommended resources, and FAQs to help you learn R.
Manuals from the R Project.
Series of tutorials for developers in R by Google Developers.
The R Journal is the open access, refereed journal of the R project for statistical computing. It features short to medium length articles covering topics that might be of interest to users or developers of R.
R news and tutorials contributed by R bloggers
You can enroll or audit them for free.
A variety of courses are offered. Prices vary.
Screencast versions of the "classic", older versions of the workshops are linked below. Maximize the viewer size and resolution for the best results...
Intro to R, Session 1 - Statistical Functions
Intro to R, Session 2 - Graphics
Intro to R, Session 3 - Data Manipulation