raster is an R package for spatial data analysis. Released versions are on CRAN. You can learn how to use it on On rspatial.org you can learn about spatial data analysis with R.
stackoverflow is the best place to ask questions if you get stuck. Make sure to include a simple reproducible example. If you have found a bug, you can file an issue.
The easiest way to get the development version is to install it from the R-universe, like this:
To install from source code you can do:
If you are on Windows, you need to first install Rtools to get a C++ compiler that R can use.