This is a reward from the quest Working the Ash Tree from Furniture Dealer Lebyos in Heidel.

> This is a reward from the quest Working the Ash Tree from Furniture Dealer Lebyos in Heidel.

This is technically correct, but what you want is the starter quest in order to get this one. Talk to Ficy in Heidel and pickup "[Processing] Learning Higher Processing Skills". You'll get "chopping: begginer", "grinding: beginner" and "heating: beginner" when you're done.

Step by step on how to acquire this knowledge in order to be able to accept the quest "[Processing] Trent Worker Experience?":

1. Open your Black Spirit. (Press "," )
2. Click the flag that says "Guide".
3. Scroll down and find and select "[Knowledge] Obtain Chopping: Beginner".
4. Exit the Black Spirit (esc) and follow the waypoint guide to Ficy in Heidel.
5. Talk to Ficy and accept the quest "[Processing] Practice Makes Perfect".
6. With this quest accepted, Lebyos in Heidel now has the quest "[Processing] Working the Ash Tree", go to him and accept it.
7. Either chop Ash Trees for Ash Timber, or rather just buy 15 timber off the Central Market (it's only around 10k silver total).
8. Press "L" to open the processing window, click "Chopping" (3rd icon from left) and process the 15 Ash Timber into Ash Planks.
9. Go back to Lebyos, talk to him, select "Chat" and give him the Ash Planks, turn in the quest and you're done.

You can get it from one of 2 quest chains:
(shorter) Bring Equipment
and
(longer) [Processing] Working the Ash Tree