i have bought the book to you today幫我睇睇我釋得岩唔岩..

不如咁寫, 唔知啱唔啱你意思:

I have bought the book for you, will send it to you today (或tomorrow, 或Wednesday等等) - 我已經買咗本書, 會今日(或明日或星期幾等等)送比你. (Send可以係郵寄或速遞等, 比較彈性.)

I have bought the book for you, will give it to you next time when we meet. (已經買咗本書, 下次見面時比你.)

2007-11-12 12:04:47 補充：
記住係for you唔係to you!

2007-11-12 12:13:45 補充：
I meant - Bought the book for you, send or give the book to you.

Today: so it's a specific time or date, so... you'd better write:

I bought a book to you today.
If the book is the one you have mentioned before, then you can write:
I bought that book/ the book to you today.

BTW, 'have buy ' is wrong.
There are no tenses will use an infinitive (to buy) with 'have '.
Different tenses for 'to buy' are:
buy(s), bought, have/has/had bought, will/shall buy, etc