Mexican flag is full of national symbolism. The green strip represents the Independence Movement. The white stripe represents the purity of the Catholic faith. The red stripe represents the Spaniards that joined in the quest for Independence and the blood of the national heroes. The emblem-shield symbolizes the Aztec heritage.
Throughout skyrim you will go to the Riften fishery and see a woman (Argonian) - No hair. She will say she might lose her job due to a Skooma addiction and needs a Cure Desease potion, once she had this a Goal will come up saying Find out the source of the Skooma.
Travel to Solstheim | Main story mode - Dragonborn TES V: Skyrim - Dragonborn Guide. Head to Windhelm and search for the proper ship in the docks. You can head there using fast travel or on foot, which you should of course know very well of. After getting there, head to meet with captain Gjolund Salt-Sage - he can be found on the first boat from the shore (as seen in the above screenshot).