[godwine]

Thanks..

but for the first 2 example, why can't it be

図書館で行く
公園に遊ぶ

When do you use NI and when do you use DE?

Also, I was going through the books and some current literature. 私, is spelled in Romaji "Watashi", and in the first book I have for Japanese language course, its also spelled in Romaji AND Hiragana this way. However, I got a hold of a really old beginner text book that suggest it was spelled as "WataKUshi" in both Romaji and Hiragana

Kanji (according to Windows Japanese IME) would produce the same thing as "私" regardless of how you spell it. I am guess that both way works? Or under certain circumstances you use watakushi? I've been using Watashi all my life (I understand that it will pronounce the same regardless)

Thanks