Question
i have a large lilie plant need to seperate when and how do i go about doing this

Answer
Hello Deford,
Separate your lilies in the fall by digging them up and separating the bulbs.  Replant in the areas you desire.  You can also do this in the Spring right after the last frost but your lilies may not bloom.  One other thing, you will find large bulbs and smaller bulblets.  The bulblets can be separated and planted in a garden bed and it will take 2-3 years for them to produce a blooming plant.  I hope this helps.
Tom