I am new in R Studio. I tried to download the libraries, but this message showed up:

require(devtools)
Loading required package: devtools
Warning message:
In library(package, lib.loc = lib.loc, character.only = TRUE, logical.return = TRUE, :
there is no package called 租evtools・> install_github('ramnathv/rCharts')
Error: could not find function "install_github"