Most people just add the map to the mod, set it's "Import Into VFS" to "false", and have the user copy the map from the mod to their ~\My Games\Sid Meier's Civilization 5\Maps folder. They then select the map in Advanced Setup, click "Back" once the map is selected, and then click on the little button called as I recall "Play As Scenario" that would then show on the normal modded-game set-up screen.
You can rework the game set-up screen to load a custom set-up page and the like, but this requires a lot more work, a re-written lua and xml file for the set-up screen, and perhaps more that I am not thinking of at the moment.
You can look in the 1066 Firaxis Scenario (assuming you have it: if not, just look at one of the others) to see what you need to do to make your mod automatically select the map when the mod is enabled. As well as all the other stuff you need to do as examples of re-working the game database to make a scenario: C:\Program Files (x86)\Steam\SteamApps\common\Sid Meier's Civilization V\assets\DLC\DLC_04\Scenarios\1066Scenario
I don't think many people have really gone the "full-on" route with custom set-up pages, custom victory scenes, and the like. Gedemon's TSL system is one example of a modded "full-on" scenario, but his code for the game set-up lua files is pretty complicated.
So far as I know there is no tutorial for Scenario Creation, either as a general tutorial or for the specifics of what you need to do in ModBuddy.