Install QGIS and access documentation
1. Download QGIS from http://www.qgis.org and install. For Windows the installation includes OSGeo4W, a Windows installer for Open Source GIS projects;
2. Documentation for QGIS is available at http://www.qgis.org as well;
3. For further documentation on how to run R in QGIS, search for QGIS processing framework.