The setting is SHADOWRUN, using 3rd edition rules (with some modification for the medium of the MUD) set firmly within the year of 2064, so keep that in mind when looking up timeline details from various sources.
If you're having troubles getting started try asking yourself these questions, and jot them down the answers as notes.
1. Where was the character born? Growing up in Seattle results in different experiences and outlooks than being born in Tir Tairngire or NAN tribal lands.
2. What was or is your character's family? What did your character's parents do? Were they married, divorced, separated, etc? Does the character have brothers and/or sisters?
3. Has the character started his or her own family? Does your character have children?
4. Where and how was your character educated? The streets? In a gang? At a university? In a megacorp?
5. What does your character do for a living? Shadowrunning may not be their only job.
6. What are your character's political, spiritual, or religious beliefs? Political alliances in 2064 are important to success, after all. Who do you ally with?
7. What is your character's moral code? Will he or she kill? Will he or she kill anyone? Will he or she kill anytime? Does killing bother him or her? Does your character have a conscience? If so, to what extent?
8. Does your character have any long term goals? (in-char goals – not maxxing stats, etc. ) Will he or she accomplish these goals above all else? Does your character have other agendas?
9. Why does your character run the shadows? Does he or she like this lifestyle? Does she or he do it for necessity or enjoyment?
12. What major flaws do your characters have? Does it cause them to run the shadows? A common example, Harlequin may be a very powerful mage, but struggles with even simple radios.
13. Does your character have hates? Do they hate megacorps, metahumans, laziness, obesity, politics, religion, BTL addicts, drunks, etc?\
Note: RACISM in 2064 /generally/ applies to race, not skin color. There are plenty of exceptions to this, however.
14. What are your character's hobbies? Are they only a gunman, or do they love art, food, have a passion for woodworking, dancing, collecting watches, members of the same sex, shadowrunning, excitement, poetry, reading, or some other activity?
15. What is your character's birth name? After all, running the shadows is an illegal activity. Having people know your real name is an issue. Does your character have a birth right? Does your character know their true name?
A few more questions you may want to answer:
1. What is the best thing your character ever did?
2. What is the worst thing your character ever did?
3. Who is your character's hero or role model?
4. What manner of dying does your character fear the most?
5. What manner of dying does your character embrace, or do they fear death entirely?