After clicking on any page, you can edit the design of the page layout. You will see the default widgets to set the content on the page layout. 
By clicking on the Preview button, you will get an idea of how the page will look. 
You can also edit the added widgets, add new widgets, and remove if not required. 
Menu and Form widgets are added for the ‘Edit Case’ page. “Menu” widget is for navigation that will display the list of the menu to navigate to other pages.
You can create a new page by clicking on the + Create button. Here you will have two options: Create a page using the Page Layout or create a page using the pre-designed Template. 
If you have selected ‘Page Layout’, select any page format, and click on the Next button. But if you want to select any pre-designed template, you will have the “Select Template” drop-down option to select the relevant template from the list.
To create a page, you need to provide certain mandatory details:
Title: Insert the title of the page.
Page URL Slug: Once you insert the title, the slug will be suggested. You can edit the URL slug. 
Page Access: You will have two options here to access the page to the portal users: Public or Authenticated
If you want to show the page before login and after login on both sides, you need to select the Public checkbox. But, if you want to show the page after the portal users log in, you need to select Authenticated option.
Note: If Page Access is “Public” then records will be displayed on the portal but your portal users can’t apply any CRUD operations on the records.
Page Nesting: Select whether it is the parent page or the module’s child page (Under Parent Page).
Select the page as ‘parent’ or the created pages will be listed under any parent page if you have selected the ‘Under Parent Page’.
Page Layout: You will get the ready-made page builders to design the page layout as per requirement else, you can select the Default Page Layout.
When creating a new page layout, you will get the reCAPTCHA option at the end if you have enabled & configured the reCAPTCHA.
Note: If the V3 reCAPTCHA is configured, only then you will get the Enable reCAPTCHA option at the time of the Page Layout creation. If you have enabled it, the V3 reCAPTCHA will appear in the customer portal for that page. 
Now, click on the Next button to design the page layout and you will navigate to the page layout settings.
Under the “Layout” tab, the different layouts (body) are provided to manage the page layout in that and display the portal content as you want it to be displayed.
Drag and drop any layout from right to left Body part. 
You can also select the Custom Page Layout as per your requirement.
If you have selected the Custom Page Layout, the custom layouts will be added under the Page layout design.