Two new sentences I made trying out more particles! Sorry for posting so much but I'm having fun learning.
ひらいくんがなんでざっかてんにいった？(Why did hirai-kun go to the store? Not sure if I need something between "なんで" and "ざっかてん")
みずきちゃんはえいがかんでえいがをみた、でもすきじゃなかった。 (Mizuki-chan saw a movie in the theatre but did not like it)
Sentence critique would be appreciated
EDIT: I often hear people saying "nani o" or "nani o sore" in animes. I get what is being said but I don't really understand how o works in that case grammatically if anybody could elaborate.