There are many books and online materials that cover all aspects of R. The name R can make it difficult to come up with useful web search hits (substituting CRAN for R can sometimes help); nonetheless, searching for R tutorial brings up useful results. Some useful resources include the following:
- An excellent introduction to syntax and data structures in R (at goo.gl/M0RQ5z)
- Videos on using R from Google (at goo.gl/A3uRsh)
- Swirl (at swirlstats.com)
- Quick-R (at statmethods.net)
At the R console, the code phrase ?functionname can be used to show the help file for a function. For example, ?help brings up help materials, and using ??help will bring up a list of potentially relevant functions from installed packages.
Subscribing to and asking questions on the R-help mailing list at stat.ethz.ch/mailman/listinfo/r-help allows you to communicate with some of the leading figures in the R community, as well as many other talented enthusiasts. Read the posting guide and do your research before you ask any questions, because it's a busy and sometimes unforgiving list.
There are two Stack Exchange communities that can provide further help at stats.stackexchange.com/ (for questions about statistics and visualization with R) and stackoverflow.com/ (for questions about programming with R).
There are many ways to learn R and related subjects online; RStudio has a very useful list on their website at goo.gl/8tX7FP.