Cells, values and your first formula

A worksheet is a grid. Columns are lettered (A, B, C…), rows are numbered (1, 2, 3…), and every box where they meet is a cell with its own address. B3 is column B, row 3.

A cell holds either a value you type (a word, a number) or a formula that calculates one. Formulas always start with an equals sign:

=B2+B3

Point at cells instead of retyping their numbers. When a number changes, every formula that points at it updates on its own. That's the whole idea of a spreadsheet.