I need help setting up column totals that allow me to add lines above and have them automatically included in the total.

HI, I am relatively new to spreadsheets. I am setting some up to keep track of income and expenses. When I set up a total line I have been using the SUM function, however, when I add a blank line above the total line and enter data into that new line, the formula in the total line at the bottom doesn't automatically update to include the new line in the total. So with a 20 column spreadsheet, I seem to have to redo all the formulas in the total line everytime I add a line to the spreadsheet. Surely there must be an easier way, but I can't find anything in the online manual that allows conditional cell numbers in formulas. My work around is to put in lots of blank lines before I set up the total line but that's not very satisfactory in the longer term. The formula I would like to put in would read =SUM(column) to add all figures in the comumn above, but alas this is not allowed. Can anyone please tell me how this is done? Thanks lots, Rick