Start learning R interactively with swirl, an R package that creates a dialogue environment inside RStudio.
To initiate a learning session, open your RStudio and execute the following code:
install.packages("swirl")
install.packages("Rtools")
install.packages("devtools")
devtools::install_github(c("swirldev/swirl", "swirldev/swirlify"))
library(swirl)
Follow the prompt and complete the first lesson.
Watch an intro into swirl by its creator Nick Carchedi. DataCamp's Introduction to R might also be helpful to hit the road running.