To care for your fabric lampshade you will need to dust it regularly to ensure the dust does not settle to stay.
If you have a perspex diffuser you will need to remove it on occasion to wash it, just tilt it vertically and pull down to remove it. Wash the diffuser in warm soapy water with a soft cloth. You can use a suitable spray to remove any streaks on the bottom of the diffuser. Never use a scourer as this will scratch the surface.
Never submerge your lampshade in water as this will cause irreparable damage.