Dear Durgaji,
Love.
Your question is vague; hence, an appropriate answer will not be possible. However, I will give you a few tips that may help you:
1) Fulfill legal formalities.
2) If you don't have budget constraints, then take the services of a professional to design your mobile van and market your products.
3) Decide on the product mix and pricing, considering the taste and economic conditions of the locals.
4) Remember that location, timings, cleanliness, hygiene, and the freshness of the food are essential factors to take care of.
If you provide further details, better guidance can be given. Anyway, I wish you all the best for your new venture.
His Blessings,
Sharad Shah