R is free to download and use. There is a large and active R community online, with many resources for learning R.
Where to Find R?
RStudio is an open source, integrated development environment (IDE) for R. It includes a console, syntax-highlighting editor that supports direct code execution, as well as tools for plotting, history, debugging and workspace management.
User can develop their own functions in R to do specific tasks (i.e., adding text to graphics, reformatting data, etc.). Before writing code from scratch, however, keep in mind that one of the main benefits of R is the vast array of pre-existing packages, written by other R users and available for download. You can find officially vetted R packages on CRAN (Comprehensive R Archive Network).
Read here about how to install packages in R.
Here are some packages that may be useful: