To make an HTML file open when the F1 key is pressed in a 4D database:
1- Place the HTML file at the same level as the database structure or in the plug-in folder (Mac4DX or Win4DX).
OR
In client/server mode, place the HTML file in the Win4DX or Mac4DX folder located next to the structure file on the server machine.
2- Name the HTML file with the same name as the database structure followed by the extension ".htm" (if the structure name is mydatabase.4db or mydatabase.4dc, then the help file should be mydatabase.htm).

If you want that file to be used as a contextual help file, you need to define named anchors in its flow. These anchors will be used as targets when that file is opened. For example, if you define "11" as being the topic ID for a form in the Help page of the form properties dialog, a matching named anchor () should be inserted in the help file. This is where that file will open when the F1 key is pressed from that form.