Here's a quick example of a cartridge with a title screen.
To do this, use the script called 'Switch Room' in the internal tab. It will be possible to write your own scripts in Lua later, but these scripts are placeholders for now.
Note that there's no need to have a controllable player actor from the start -- you can introduce the player after the title screen / intro or whatever.
Open the Internal objects tab (on the right of the navigator -- it shows 'Actors' by default)
Click on Internal and then open Scripts
Place the 'Switch Room' script somewhere in the room, and set the trigger to SYSTEM:BUTTON:SHOOT.