"Editing mode" in Microsoft's Excel spreadsheet program refers to the state at which a cell is activated. You must initialize editing mode to edit the content of the selected cell. Excel has a few ways to switch to editing mode after you choose a cell to modify.
Click the "File" Ribbon tab. Click "Open" to view a list of Excel files. Double-click the file you want to edit to load it in the software.
Click the cell you want to edit. Use the mouse to click the formula bar at the top of the window. The cell activates, and it switches to editing mode. You can also double-click the cell to activate editing mode, or you can press the "F2" key.
Press "Enter" after you type in your edits. Pressing "Enter" saves the cell changes and displays the results of a formula, if you created a calculation.