방금에 뭔가 했어요 translate could translate to I just did something.. but 방금 means, a moment ago/just 그냥, 텔레비전에 뭔가 봤어요 Just, I watched something on television If your friend asks what are you doing? 뭐 하고 있어요? You can reply 그냥... same old/nothing interesting This is rude, shows no interest. 왜 그럼 했어요? Why did you do that??? 그냥... just because... Or if you have no good excuse! haha 감사합니다!

just means 그냥 or 단지 something 어떤 어제 난 어떤 걸 봣어

I just watched something. just means "not having any special idea" "그냥" so it can be translated in "나는 그냥 뭘 좀 봤어".

"그냥" would be fine for that, "난 어제 그냥 something을 봤어." \^o^/