You have to upload return by filing details of authorized representative who is filing the return on his behalf. There is an option in ITR askng is return filed by authorized representative, select that as yes and fill in details there.
If you have downloaded ITR utility or if you doing by any software you can see that there is specific option where the question is asked that is the return filed by authorized representative you have to select yes from drop down and fill in the details. In case stil not clear you let me know that you are filing return through utility or software i will be able to guide u exactly by sendng u screenshot of that option.