To get a custom crest in Imperium Nova (a picture on your crest besides one of the default pictures shown), you'll need one of two things: the ability to make your own crest, or access to a person who does. Luckily, if you are not skilled in Photoshop or any other image editing software, there are several players that will happily fulfill a request to have one done for you.
List of Players to Contact:
Once you have your crest in hand, you'll have to email Simon with the file and tell him the colors and crest background you want it implemented in. Because it's custom, you won't be able to change the crest at will like default crests. Simon has said that he'll be picked the best custom crests to be used in V2.0.
If you do know how to make your own crest, here are the rules you have to follow: