are there sites where i can send free messages to chinese nu

Probably not...and if your chinese is not exceptionally good,i'm afraid you would not know how to use one were there any since not even ourselves are using it.sorry for that.
BTW:why not simply use emails?
再问： if i will send message to my friend by e-mail they will read when they will online, so if i will give them site where they can send me free sms to my mobile phone, i will read that in time.
再答： Nope mate. All SMS sites require a pay. Try skype or other IMs for phones perhaps, though you might already have done that.