The simplest checkbox (I think) is from the Forms toolbar.
So View|tool bars and show that Forms toolbar.
Click on the checkbox and then click on the topleft corner where it should be
placed. Then draw to the opposite lowerright corner.
When you've placed it correctly, right click on it and select "Format Control"
On the Control Tab, you can assign a cell link that you can use to determine if
the checkbox is checked or not.
=if(A1=True,"It's checked","It's not checked")
(If I chose A1 as my linked cell.)
