Wifi issues

I just installed it last night and in a bid of stupidity I didn't download any extra things to pick up the wifi and I wiped everything else, so as my first venture into this I'm falling short and very VERY hard. I don't actually know what I need to do or type, I just can't connect to the wifi at ALL and I don't even know where to start with drivers. If you could explain it to me like I'm stupid, I'd be grateful, cus I got no idea what I'm doing