Just put the words you want in the blanks inside {}. So The Big Bang Theory would be The {Big} {Bang} Theory, and then it would come out as The ___ ____ Theory.
Sorry. Type your desired text in the answer column, puting {} around which words you want a blank for. So, you would type something like "Kuala {Lumpur}" and it would come out as Kuala ______. One problem i sometimes have, which may be happening to you is that you didn't change the answer. In the answer options, you type in the entire text in the text row. You then have to change the accepted type-ins, so that only Lumpur is needed, not the entire phrase Kuala Lumpur. Hopefully this makes sense.
great quiz though, although hard for non-americans