Helen, 1.Whether they are OK or not would depend on the context. Is this happening in the present or past? We don't know from that example. 2.I didn't know ABOUT it before today. I think this is what you are trying to express

I'm also learning English. but I think the first question must be clear "Are the both sentences correct?" instead "Are they both ok?" "The book is/was new to me" if you speak in the present time you can use the verb "is" : This book is new .." :) Regards