I'm not sure that we have any tutorials that speak to this exactly but in essence the checkbox form element can be thought of as a text input that the value is preset on, and will be submitted if checked.
To make something active/inactive the easiest way is to have a column in your db for this. The value should either be a 1 or 0. A 1 would indicate active and a 0 inactive.
To record these details on the admin page just set the value of your input to be 1, then change the type of the input to be a checkbox. That is all for the insert page.
On the update page you will just need to specify that the checkbox should be checked if the recordset value is equal to 1, other that that it is the same as the insert page.