How would I go about making my game work like this?

So my idea for my game is the player has to collect a certain number of hearts and then collide with a certain object (in this case a princess) and then the player will have won the game. How would I go about doing this?

Side note I also have an idea that the player can collect tacos and after they've found all of the taco's the game displays a message. Any help on that would also be appreciated. TIA

 

You want to ask this question in Getting Started forum section. Also please follow some tutorials to get basics concepts.