Carry out the following steps to create a custom Help for this Page option on an opportunity record using a Lightning Component, Lightning Action, and a PDF document:

1. Click on the Setup gear icon, as shown in the following screenshot:

The Setup gear icon is located in the top right-hand area of the main Home page.

2. Click the Developer Console option, as shown in the following screenshot:

We will be presented with the Developer Console window.

3. Click on File.
4. Click on New.
5. Click on Lightning Component, as shown in the following screenshot:

We will be presented with a New Lightning Bundle dialog.

6. Enter OpportunityHelp in the Name field.
7. Optionally, enter a value in the Description field.
8. Click on Submit, as shown in the following screenshot:

9. In the resulting component page, paste the following code:

 
<aura:component implements="force:lightningQuickAction"> 
  <a href="{!$Resource.HelpText}" target="_blank">
  Help for This Page (New Window)
  </a> 
  <iframe width="100%" height="400px;" style="border: 1px solid"
  src="{!$Resource.HelpText}" /> 
</aura:component> 
 

10. Click on File.

11. Click on Save, as shown in the following screenshot:

We will now configure a Lightning Action that references the component.

12. Click on the Setup gear icon, as shown in the following screenshot:

The Setup gear icon is located in the top right-hand area of the main Home page.

13. Click the Setup option, as shown in the following screenshot:

14. Navigate to the Opportunity customization setup page, by clicking the following: Objects and Fields | Object Manager | Opportunity | Buttons, Links, and Actions.

Locate the Buttons, Links, and Actions section on the right of the page.

15. Click on New Action.

We will be presented with the Opportunity Actions - New Action page.

16. Select Lightning Component for the Action Type.

We will be presented with the Lightning Component selection.

17. Select c:OpportunityHelp from the Lightning Component selection.
18. Enter 500px in the Height textbox.
19. Enter Help for this Page in the Label textbox.

20. Optionally, enter a value in the Description textbox.
21. Click on Save, as shown in the following screenshot:

We will now modify an opportunity page layout to add the Help for this Page Lightning Action to the opportunity record page:

1. Click on the Setup gear icon, as shown in the following screenshot:

The Setup gear icon is located in the top right-hand area of the main Home page.

2. Click the Setup option.
3. Navigate to the Opportunity customization setup page, by clicking the following: Objects and Fields | Object Manager | Opportunity | Page Layouts.
4. Select the required page layout by clicking on the page layout name from within the list of available page layouts, as shown in the following screenshot:

5. Override the predefined Actions in the Salesforce Mobile and Lightning Experience Actions section by clicking on override the predefined actions, as shown in the following screenshot:

6. Drag the Help for this Page Lightning Action to the Actions section on the page layout, as shown in the following screenshot:

7. Finally, click on Save.