An extremely stupid question... I'm a newbie

Ok, this is gonna sound stupid. But I'm new to Unity and Javascript (and making games in general), and I need to know. Before now, the only "programming" I have ever done is messing around on an ancient Apple 2e computer and using a graphical programming software to program home-made LEGO robots. But, about my problem. Basically, I am making a platformer where you collect 10 items around a map within a time limit. If you run out of time, game over. So, I have the countdown timer working fine (It loads the "Game Over" screen after a minute or whatever time I tell it), but I need help getting the items to work. There are 10 in each level. So, here is how I was thinking the script would work. When the character hits a collider around the item, it would ad 1 to a counter thing (Variable, correct?) and then destroy the object. Once the counter reaches 10, the player must have collected all 10 items, and it loads the next level. Simple, but I have no clue how to code it. Can somebody either write a quick sample piece of code giving some ideas or refer me to a scripting tutorial? Thanks!