To summarize:

To use the Fill Handle:

1. Enter the first number in the cell where you want the series to start.
2. Click and hold the fill handle with your mouse.
3. Drag the fill handle down to the last cell where you want the series to end.
4. Release the mouse button.

To use the Fill Series:

1. Enter the first two numbers in the cells where you want the series to start.
2. Select both cells.
3. Click on the "Fill" button in the "Editing" group on the "Home" tab.
4. Click on "Series" in the drop-down menu.
5. In the "Series" dialog box, select "Columns" in the "Series in" section.
6. In the "Type" section, select "Linear".
7. In the "Step value" section, enter "1".
8. Click "OK".

I hope this helps! Let me know if you have any other questions.