The latest buy back which wipro has announced will be conducted on a proportinate basis via tender offer so in this case one has to fill form and submit.
Check this link to know more about buy back via various routes and its implications.
If you are holding the shares as on the record date, you will receive the tender form and letter of offer to your email and postal address from the company.
Note the quantity you are entitled to, price and the period of offer.
Give the details to your stock broker, they will be able to place the bid on your behalf.