does anybody know how to reprograme the key fob

the reason i ask is that my old one fell apart in my hand the other day, i went and got another fob and was told it could be programmed at home
tried but still can't get anything out of it

HELP !

It needs the programming unit that Lexus dealers have.

are you sure as it was the parts lad at the local lexus dealer what told me that you could do it yourself.................