Obviously read the Drivers Manual
FIRST to see what it advises, but this looks relevant:
http://www.askthemechanic.co.uk/makes/audi.html and says:
DIESEL PARTICULATE FILTER WARNING LIGHT ON?
If the DPF light is the only warning light on, you should drive vehicle at over 2000 rpm (to raise exhaust temperature) for 20 minutes without delay, this should regenerate the particulate filter (burn off the accumulated soot) and the light should go out.
If you have DPF light and the engine management light are on together, have vehicle towed to dealer. The dealer will be able to make the vehicle, with the aid of diagnostic equipment go into forced regeneration and clear filter. Don't run vehicles with diesel particulate filters on 100% bio-diesel only use EN 590. Only use low ash engine oil (VW 507 00).