Hi,
On the class website, under handouts, there are a couple choices
for setting up your computing environment (will discuss the
tradeoffs between Windows and Linux in section). You should
view these documents on-line -- there are links built into the
.pdf files that will take you directly to the appropriate
installers.
Thus, if you're trying to install R for Windows, look at the
handout and click on the blue box around the R and it should
take you to the installation page, which is:
http://www.cran.mirrors.pair.com/bin/windows/base/,
for your reference.
Best,
Olivia