Mangal Dosh Puja is a Hindu ritual performed to appease the planet Mars (Mangal) and remove its malefic effects from one's horoscope. Ujjain, a city in Madhya Pradesh, India, is considered a holy city and a popular destination for performing this puja.

To perform the Mangal Dosh Puja in Ujjain, one can follow the below steps:

1. Visit the Mahakaleshwar Temple in Ujjain, which is one of the twelve Jyotirlingas (sacred shrines of Lord Shiva) in India.

2. Contact the temple authorities or any priest nearby to arrange for the puja. They will provide you with all the necessary information and items required for the puja.

3. The puja usually starts with a bath in the holy river Kshipra, followed by offering prayers to Lord Shiva and Goddess Parvati.

4. The priest then performs the puja by chanting mantras and offering various items like flowers, fruits, Mangal Dosh Puja Ujjain and sweets to Lord Mars. The puja may also involve the recitation of Vedic hymns and the lighting of lamps.

5. After the puja is complete, the priest will give you prasad (blessed food) and a small piece of red thread or "Mouli" to wear on your wrist, which is believed to ward off the negative effects of Mangal Dosh.

It is important to note that Mangal Dosh Puja is not a one-time solution, and it may take multiple pujas to see the desired results. It is also recommended to consult with an experienced astrologer to determine the best time and method for performing this puja.