There are four guilds, each with one or more different missions, which are outlined
here. The Mage Academy wants one of three different magickal artifacts; the Black Dagger wants the heads of one of four orc thieves, and if you're feeling ambitious, there's a bonus if you kill one of their accomplices; Skjalborg Academy wants a weapon belonging to one of three orc generals; and Auzial Academy wants you to collect ingredients required in making one of two potions.
The idea is that you select one or more missions (bounties) that one of the guilds is offering, and write a thread where your character is accomplishing that mission. The posts by each of the guild leaders offers some advice on how you might accomplish it, and where to go. Also,
this thread mentions where to go for different bounties, and once you have a thread started, reply to that RP Discussions thread with the link.
How you accomplish your chosen mission is basically up to you. You'll be awarded silver for accomplishing the task, and if you really plan it out, chances are you'll get a bigger prize (though the criteria on how silver will be awarded is known only to the judge(s)).
Does that clarify things at all? If you have more questions, please try to provide more specific detail as to which part is confusing you, so that I can better answer.
