Right click on any visible tool bar and select the CONTROL TOOLBOX toolbar.
Select the check box from the list of available controls and then click in
the work sheet where you want to place it.
The first buttonon the CONTROL TOOLBOX has a triangle/pencil/ruler on it and
this is the design mode toggle. Click to turn this off so that you can use
the check box. To modify the check box (change its label, add some code,
etc...) turn design mode back on and right click on the control in the
worksheet. Select from the list of available options.