I have been gifted some beautiful aran wool but want to knit a DK pattern with it, how do I convert it please ? I am a novice 
Welcome to the forum!
What is the name of the pattern you want to knit and what is the name of the aran yarn?
It can be a bit of a stretch going from DK to the heavier aran. To be sure you should probably knit a swatch at least 4 1/2’ x 4 1/2" and measure stitch gauge over the middle 4". That’ll give you an idea of the knit fabric as well as sts/inch.
Blankets and scarves are relatively easy to convert. Sweaters not so simple.
If you tell us which DK pattern you want to make, we might be able to find you a similar design that is written for aran weight.