Wool is naturally self-cleaning, which means that it does not need to be washed often. Simply airing it outside overnight or hanging it in a humid bathroom is often enough to restore its fresh scent. If the item has a stain, you can easily spot-clean it with a small amount of gall soap.
If the item needs to be washed, it can be machine washed at a maximum temperature of 40°C / 104°F(so it can simply be washed together with your regular laundry!). Use a mild, natural wool detergent and do not use fabric softener. After washing, gently reshape the item and leave it to dry flat (do not dry it on a radiator or in a tumble dryer).