For past 1 week I got a layer of white substance under by penis skin and skin also gets tight and there is also problem in pulling it back
You may have a yeast infection or balanitis. I recommend using an antifungal cream like Clotrimazole 1% cream. Apply a thin layer twice a day for about 1-2 weeks. Make sure to keep the area clean and dry. If the symptoms persist or worsen, please consult a doctor for further evaluation and management.