Margarte is a Nord merchant in Leyawiin. She can be found either in the Great Chapel of Zenithar in Leyawiin, in her house directly across the street from the main entrance to the temple, or just outside the city collecting alchemical ingredients.
Modryn Oreyn sends the Hero to Leyawiin to investigate what has happened to three other Guild members. Apparently, they have been drawing a lot of negative attention towards the Fighters Guild and causing trouble at the Five Claws Lodge.
She is available for Journeyman Mercantile training whenever she is not sleeping (12:00 AM to 6:00 AM), eating breakfast (6:00 AM to 8:00 AM), collecting ingredients (12:00 PM to 6:00 PM), doing Sundas worship (Sundas from 8:00 AM to 10:00 AM), or eating dinner (8:00PM to 10:00 PM).
This means she is available for training most days from 8:00 AM to 12:00 PM and again from 6:00 PM to 8:00 PM, and from 10:00 PM to 12:00 PM. She will most likely be at the chapel during those hours.
"My name is Margarte. Professionally, I'm a trade consultant...I offer Advanced Mercantile training, by the way...But my real passion is alchemy. I love brewing up new and interesting potions...just for fun! It's a pity my busy consulting and training schedule leaves me little time for gathering ingredients...And heavens forfend that my husband, Eitar, devote a few minutes from his all-consuming hobby...stirring up trouble between Khajiits and Argonians, to help me find ingredients."
- Leyawiin "I'm sure there's an abundance of exotic ingredients to be gathered nearby. In Blackwood, for example, or along the Niben."