You get your horse at the towns. Look on your map for a horse head icon. You can change the look of your equipment to imperial by right clicking and selecting the imperial style option in the right click menu.
Go to any stable, buy the 1 gold Imperial white horse.
Press I for inventory, right click the item and select "Convert to Imperial Style" it will tell you the item will be bound to your account once converted and ask you to confirm, say yes. Some items like dropped set items can't be converted to Imperial style but any crafted or regular drop items can be converted.
With the Imperial edition you can create an Imperial character that can craft Imperial style as their native crafting style. Crafted Imperial gear can be sold or given away/traded just like any other crafted gear.
Edited by Jennifur_Vultee on November 29, 2014 1:59AM
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