Your screen of R-Studio has 4 parts.
Left - Up is where you handle with scripts and other file formats - this file needs to be run as @StatSteph wisely answered.
Left - Down is console and background jobs. In the console any code you enter automatically runs.
Right - Up - usually shows environment data (variables, etc.)
Right - Down - usually shows plots and help.
You can change any of those by choosing: view --> panes --> panes layout