The absolute first thing you should know about standard R workflows is that programs are not generally written directly at the interactive R interpreter. Instead, R programs are usually written in a text file (with an .r or .R file extension). These are usually referred to as R scripts. When these scripts are completed, the commands in this text file are usually executed all at once - we'll get to see how, soon. During development of the script, however, the programmer usually executes portions of the script interactively to get feedback and confirm proper behavior. This interactive component to R scripting allows for building each command or function iteratively.
I've known some serious R programmers who copy and paste from their favorite text editor into an interactive R session to achieve this effect. To most people, particularly beginners, the better solution is to use an editor that can send R code from the script that is actively being written to an interactive R console...