If your terrace canopy's frame and substructure are made of aluminum or steel, simply clean the material using water and a mild detergent. Avoid using cleaning products that have a scouring or abrasive effect, since these can attack the coating and the material.  

Alternatively, you can hire a STOBAG specialist partner to clean your system regularly. More about cleaning sun blinds.  

You usually need a building permit for a terrace canopy, even if it is of a simple construction, since it is often considered as a conversion of an existing house. It is therefore advisable to check with the relevant building authority beforehand.