Total Excel Noob with what is probably very easy question

Sorry in advance for my ignorance.

What I want to do is to make a new column with a formula that uses existing data in the spreadsheet. This is for baseball statistics. My problem is, I can only get the formula to work for one cell and not all the way down the column.

Example...

I want to calculate the amount the amount of homeruns and divide it by 215 for each player on the list so that they have a new HR % in another column. I can do this for each individual player, but not for every player who are already in the sheet. There are 1114 players listed...I don't feel like doing this 1114 times.

How do this so every players homerun% of 215 will be displayed all the way down the column without me doing it for each cell?

Hope I explained this well enough. Thanks in advance for any help you can give me.

Apologies for the post title. I assumed the question was so easy that anyone frequenting the board would know how to answer it, not to mention, it is difficult to describe in a topic heading only.

Thanks for #2. I'll try it out.