@mioumiou for your permatan start with an aggressive exfoliation regimen. I will tell you what has worked for me. I alternate between GA and LA,but I prefer LA because I feel a tingle that assures me it's working. I worked my way up from 15% - 17% LA lotion.
To make a 17% lotion , you'll need to add 38 ml of 90% LA to to 162 ml of Vaseline intensive or aveeno lotion.
You'll use the la lotion am and pm from Mondays to Thursday, with g n g ,toujours jeune soap.
On Thursday use Dead Sea salt soap to shower and moisturise with mango butter/Shea butter.
Saturdays and Sundays shower with dove/geisha soap and skin build with mango butter, Olay total effects or even your jergens healing lotion.
Do this for a month or 6 weeks. This should lift your permatan or brighten you at least. You can now decide to further lighten your skintone. HTH