How do I Create Building System?

Hey, There!

I'm making a top view survival game. I've made a lot of progress. But the missing part is building system. I created a crafting system and inventory system. The player can craft knife, clothings, wood block etc. I can see the wood block in my inventroy when I crafted one. I want to place it on the map.

I created some events like this:

But the problem is other blocks. I want to place stone blocks and iron blocks too whenever I want. How can I select the block which is wanted to place on the map? Sorry for my bad english.

When you click on a sand tile, it should open the inventory, then whatever the player selects it will spawn that item. If you have an inventory, might as well use it!