Formatting

I have an excel worksheet that that I am looking to format easily rather than the tedious way I had attempted. Column A and B are both dates, with B being dependent on the date in column A. I have formatted Column B based on the following formula for cell B1: =A1+19. I had attempted to go through and format each cell independently, however, I now have over 300 rows to complete and doing this manually is a pain. Is there a way to format the entire B Column so that each row will pull the information from the corresponding A Column date and give me the date that I need? For clarification, is there a way to format the entire B column so that when I enter information into A1 it will give me the correct date for B1, A2 for B2, and so on?