To add additional details to your Single Property Page Website, click on the "Details" tab at the top of your transaction dashboard:
OR open the right transaction details pane by clicking on the "bars" icon in the upper right and the edit "pencil" icon:
In the "Details" page, you can add as many details as you want. Just add/edit details as you see fit and click "Save". These updated details will then show up on your public marketing page, except for the Contract Date and Price, which will always stay confidential just to you and your transaction members.