Are you doing your polytechnic? If yes then the options for you are:

You can write JEE Main and then qualify to write JEE Advanced. This way you can do Computer Science at the IITs. 

The next step is to apply for lateral entry. It is for diploma holders who go to study engineering from the 2nd year onwards. This is dependent on the state you belong to. For eg Maharashtra has a separate admission rule to what Karnataka will have. so if you tell us which state, we shall give you more information.