You’re almost there 
The final html file is generated as part of the ‘Package’ process. You’ll need to run this process from UnrealFrontend.
The general flow is going to be:
- Launch UnrealFrontend
- Switch to ‘Game Launcher’ tab
- Choose ‘Advanced…’ at the left
- Create a new profile (if one does not already exist) by clicking the ‘+’ button in the upper-right
- Build: Do you wish to build? (tick this checkbox)
- Cook: By the book (selected any maps you want to cook under the Cooked Maps group)
- Package: Package & store locally (fields can be blank)
- Deploy: Copy to device (add a new group and tick item with HTML5 icon)
- You can now ‘Launch’ the build process
Provided that the build compiles successfully and the cook process doesn’t throw any errors, you should find a .html (and some other data files) in the same directory as UE4Game.bc.