How Do i make a event that works like an "IF"

im trying to do an shop, on the shop theres 3 slots, each for an upgrade. for each upgrade you need to buy like 5 something and then the upgrade will apear on a slot, im trying to make if the slot 1 is fill them the upgrade apears on slot 2 and so on but i dont know how to do that

Ifs are 'conditions' in Construct, they appear on the left, press C to add one to an event such as 'variable = 5' meaning if variable = 5 then do something (the action on the right).

construct.net/en/make-games/manuals/construct-3/project-primitives/events/conditions