this is what's the problem about : tikzz has the critical strike from sword master (is that the right name?) and he wants to put it on a tower, but as you may know, hero abilities can't be put on buildings (at least not under WE but i don't know with WEU). Basically, what trikzz asks is how to make a critical srike upgrade, not how to put it on a building's upgrade list.
4. Below it is "Techtree - Requirements". Double click it and click the "Add Tech Button".
Add your upgrade made from number 2.