Not gonna call you stupid. 
Tablo channel rescans can be performed from the Tablo Settings page via a web browser at this address:
http://my.tablotv.com
Scroll down the settings page, and in the Guide section you’ll see Edit Channel Line up button.
Click that button, and scroll down to the Rescan Button, and click it.
After the rescan completes, remember to select the channels that you want, and unselect the ones you don’t want, and then click on the Add to Guide button.
Then it’ll take about a minute per channel to finish downloading the new guide info.
The settings screen should display the guide download progress.
It’ll go thru 2 download cycles before it finishes.
I believe you can also perform the above via the Android, and iOS apps.