Once a page is created, you can edit its content at any moment. Only some zones are free for edition. These are the zones created as 'client space' in your models.
A page is structured with content rows, which you can consider as data pack piled up once on the other. Packs can be of various type and you can create very specifics content rows function of your needs.
There is two phases you have to respect in order to change the page content :
- Create its structure : that means add or delete the row(s) required.You can add or delete a row at any moment.
- Edit the rows content.
The first phase is very important. Even if you can re-order the content rows ou edit them whenever you want, you won't be able to change your rows without loosing their content.
Take your time to define your page structure and how you want to display your content, it'll directly impact the users comprehension as well as search engine optimization.