Spreadsheet formulas for going accross and down

Hello,

I am new to using spread sheets on Excel and am wondering how to enter the formulas to achieve the sum at the right of the columns and also at the bottom of the rows.

For an example I have column C as a credit D as debt and a few more as labor debt and expenses with the last three columns as GST, Balance, and Net .

At the bottom right when I'm done I have the profit after expenses.