Spreadsheets aren't a lot of fun if you aren't a numbers whiz. When you open a word processor, it's fairly obvious that you need to start typing words to make anything happen. It's less obvious what to do with all those boxes in a spreadsheet. In spreadsheet parlance, the little boxes are called cells. A cell is the intersection of a column and a row. Columns are named with letters, and rows are named with numbers, so a cell gets it's name from its column and row location, such as A1, which is the intersection of column A and row 1.
So, you type in numbers in your cells and then use Excel's formulas to perform mathematical operations on them. You use the cell names in your formulas. For example, suppose you wanted to add the contents of the first and second rows in your spreadsheet. So you type numbers in cells A1 and A2. Then you'd put your cursor in cell A3 (the third row in the first column). In the formula bar at the top of the window, you'd type =SUM(A1:A2) in the Excel formula bar.
Here's a time saving Excel tip. When you need to create a row or column of numbers in a sequence, you need only type the first couple of numbers. Type the first couple numbers in the series, then highlight those cells and all the other cells that you'd like filled in. Then choose Edit|Fill|Series. Excel figures out the next entries for you and puts the numbers in the cells.
Another handy feature is the ability to freeze rows and columns. As you create larger spreadsheets, you often aren't able to view all the column or row titles and the data at the same time. So to solve the problem, you can "freeze" rows or columns. For example, to Click the row number below where you want the split to be (or the column to the right of where you want the split) and choose Window|Freeze Panes. To remove the split, choose Window|Unfreeze Panes.