"This is an old French table."
Translation:هٰذِهِ طاوِلة فَرَنْسِيّة قَديمة.
The option is available on the fullstop similar to how you can select exclamation marks in English. Type ه then press and hold . there just select the dagger alif like this ٰ and it'll pop on top of the letter like this هٰ. There are other options all of which can be applied on whatever letter you need. Hope this helps.
The dagger alif is absent in most Arabic keyboard layouts. You should be able to get by without typing in the diacritic—if it is being marked as a typo or an invalid response, report it to the course contributors.
Even most people omit writing the dagger alif in formal texts—the exception to this is for classical literary texts like the Quran.