Assuming UE4.11 9probably same for 4.12), and visual studio 2015 community are installed you can use option a or option b for any step along the way (try both just to learn how it works):
1a: From the unreal project browser, create a new UE4 c++ project (so that it creates a solution file)
1b: From an existing UE4 project create a new c++ class (so that it creates a solution file) doesn’t matter what kind.
2: When it opens visual studio you can just close it out if you’re using step 5a.
3a: Navigate to the project directory (Or just right click on content, select show in explorer, then go up a directory), create a new folder “Plugins”. DO NOT create this under the content directory, has to go in the project directory above it.
3b: Open Edit>Plugins from the UE4 editor, then click new plugin at the bottom right pane. (plugin name) This will create the Plugins folder for you, and your new plugin inside of it.
4: Copy the (plugin name) folder out of the zip file and into the Plugins directory.
5a: Close the UE4 editor and reopen the project. It will ask you if you would like to rebuild. select yes.
5b: In UE4 editor click File>Refresh Visual Studio Project, then open the solution in visual studio (double clicking the .sln file should do), right click on the project in visual studio, and select build. Restart the UE4 editor.
If you hit a snag, it’s almost definitely a visual studio problem. Make sure the project builds properly if you just ask it to create a new c++ class. if that won’t build, try reinstalling VS2015 (Remember community version is free so long as you login with your microsoft account inside the Visual Studio Application)
Cognition Tom helped me with this ages ago, hope it helps out… hunt him down and thank him.