To get Maple to do computations for you, you have to type in
commands. In a Maple worksheet, you can only type in commands at a
input line, which begins with the
input prompt, >. When you first start up Maple, the first
line of the worksheet is always an input line. When you load a
worksheet into Maple, an input line is always added to the end.
To type and issue a command in Maple, first use the mouse to move the cursor to an empty input line and click the left mouse button to select that line for typing. Then type in the command and end it with a semicolon (;). To issue the coommand, press the return key. The output of most commands will appear directly below the input line, the main exception being plots, which appear in separate windows. This region where output appears is called a Maple Output Region.
If the output of the command is not what you wanted, perhaps due to a typing error, you can use the mouse to move the cursor back to the input line and correct the command. Use the arrow keys to move around in the line and the delete or backspace key to delete unwanted characters. Once you have corrected the command, you can press the return key to issue the command. You don't have to move the cursor to the end of the line first.
When you go back and change a command that has already been issued, the old result is discarded and replaced by the new one.