The basic workflows for googlesheets can be found here:
https://rawgit.com/jennybc/googlesheets/master/vignettes/basic-usage.html
If you know the name of the worksheet, you can find it by title with:
result <- googlesheets::gs_title("the_title_here")
You can then see all of the sheets/tabs in the worksheet with
googlesheets::gs_ws_ls(result)
Then you can read it in with googlesheets::gs_read().
googledrive will authenticate you to access your drive, etc. to allow you to perform the operations aobve.