You will need to take it on a long run (say around 20 miles or so) at a moderate speed but at high revs (not 5th or 6th gear) so that the pressure builds up to break up the collection of soot in both the EGR and DPF.
Try to keep the speed and revs constant so motorway is probably best and later in the evening.
Keep any eye on the engine temperature but it will go slightly higher whilst trying to purge the EGR/DPF.
Also, it may be accompanied by a burning smell but this is part of the process.
After you finish the run, allow the engine to cool down for a period.
I would aim to give the car a run at least once a week to ensure the engine does not clog up in the future