Please help me, I'm trying to update my version of R

I?m a newbie running 3.2.4 on a mac equipped with Yosemite (10.10.5).

I want to update to 3.3.1 and have downloaded the package, but have not been able to install it.  I?ve tried install.packages("R-3.3.1.tar.gz?) and install.packages("R-3.3.1.pkg?) after downloading both files.

I get an error msg - "package ?R-3.3.1.pkg? is not available (for R version 3.2.4)"

I know this question has shown up on several message boards but I?m having trouble understanding the process.

Is there a straightforward way to update my version of R and, if successful, will R automatically work with the packages I?ve installed?

Ken Nanus
kmnanus at gmail.com
914-450-0816 (tel)
347-730-4813 (fax)