Speak with Pathstalker Kariel - the Rogue class trainer - inside the Sunspire on Sunstrider Isle.
As you advance within your class, you will want to take advantage of the training that your class trainer can provide you. For young rogues here on Sunstrider Isle, your trainer is Pathstalker Kariel. Speak with Kariel and see what training he has available for you. The things he will teach do have a cost, so bring some coin with you.
Kariel - as with all the trainers on Sunstrider Isle - is inside the Sunspire on the lower level.