If you are planning to do the R assignments on your own computer (recommended), then here is a quick outline for obtaining the software.
There are two separate software programs. Most people find it easier to use RStudio. than just R, but you need to install R first before installing RStudio (analogously speaking: you need an cell phone before you can use an cell phone case). If you have R and RStudio from a previous course, you still need to update to the current versions!