Warning in install.packages :
package ‘ggplot2’ is not available (for R version 3.6.1)
Warning in install.packages :
unable to access index for repository https://cran.rstudio.com/bin/windows/contrib/3.6:
cannot open URL 'https://cran.rstudio.com/bin/windows/contrib/3.6/PACKAGES'
This suggest you are not being able to connect to the CRAN repository. Is your internet connection behind a proxy server or firewall? That is usually the case when you are at work or school.
Thanks for suggesting a solution. It's true that often people get confused because installing a package isn't the same thing as loading it!
However, the original problem seemed to be a common error message that comes from install.packages() when R can't reach the internet, so I suspect that the internet connection problem would need to be resolved before the questioner could take your advice.