The pics you have posted suggests its a Fungal infection but we need to check other areas affected and also some more information like duration etc to confirm the diagnosis.
Once diagnosis is confirmed we can give proper course of antifungal medicines to cure it.
Usually with proper medicines it clears completely in 4-6 weeks and marks may take few months to fade completely.
Next Steps
Do not apply any cream that contains steroids( all combination creams or creams containing mometasone,etc or) as it will only provide temporary relief and spoils the overall infection
Health Tips
Consult a qualified dermatologist and avoid self medications