Hello student admission in Delhi University for Bsc hons course is through cutoff and marks secure in last examination that's your marks in class 12 Board. You need to fill the application for online or offline and after that you need to check whether you're eligible for which college as per your Marks.

For more updates refer to the link mentioned below - https://www.google.com/amp/s/university.careers360.com/articles/du-bsc-application-form/amp

Feel free to comment if you have any doubt

Good luck