Good day my daughter is 4 and every time she pees she says her private area is sore.

Tub time: If you set her in a warm tub of water & tell her it is okay to pee, the warmth will relax her muscles & it won't hurt as much. This often comes from not rinsing her bottom well after a bath, soap coats the pee hole & irritates. Bubble bath does the same. A good rinse with a hand held shower nozzle/plain water can help. If it persists, she needs to be checked for a UTI.