Dear Aditi, the first step is to fill the IPU form. IPU releases form every year and you have to fill the form carefully. 

The counselling of IPU and DU generally takes place at the same time so both the universities will release the list of candidates in a sequence. That sequence will be followed during the counselling. And if your name doesn't appear in the list that means there is some error in your form. IPU will release a separate list of those students who have made some error in form filling and the corrections also to be eligible for counselling. After that another proper list will be released containing the names of all the eligible students. 

Try to visit the main website of IPU regularly as important notices comes frequently. 

After that one more list be released in which the counselling date will be mentioned. 

As per the list you can attend the counselling. 

All the best 

Hope this helps