Russian ж is not the same as 'zh'. And ш is not really 'sh'. You have to really listen to these by native speakers for a while. Then you get it, that the tip of the tongue is doing something different for the Russian ж и ш. Like a little cupping back. Maybe they can describe it to you. Without doing a lot of listening, it won't come to you properly. Once you can get something close to the Russian ж и ш you will feel how tongue really is in position for hard sound (backed), not English zh, sh (fronted). Щ is fronted.