When you get your data into a Google Spreadsheet, it should be in separate columns. You will have the spreadsheet do some calculations for you : mean, 3 medians, mode, minimum, maximum & 2 ranges.
You put an equal sign and a formula (sometimes called function) into a cell. You need to know which cell has your first piece of data (like E1) and which has you last (like E250).
Example =max(e1:e250) finds the maximum value in the data.
You should label your calculations by typing in the cell next to it what it is.
If you are wondering what other formulas & functions it will do, click on "Insert", then "Function", then "More".
I just found out there is a "Quartile" function to find the 1st & 3rd quartiles for a box & whisker plot.
Now it is time to make plots of your data.....