Resources for R
R for Beginners is a good tutorial for beginners with descriptions of every function described. This will not describe how to install R so you will have to already have R installed on your machine to use this one.
Data Camp provides a 4 hour free (you do have to register with your name and school) beginner course to introduce you to R. This course will run R directly from your browser so you do not have to have it installed on your machine to learn how to use it. This is a good way to get hands-on experience using R.
Excellent YouTube Resources:
For Advanced Users: Consider Learning R for in-depth tutorials.