To join Al-Qaeda, as to do virtually everything else, you have to fill out an application and be accepted.
Michelle Malkin posted this in January 2006, but ABC News has just noticed, and in light of Padilla's trial it may be worth another look.
"Key Evidence in Padilla Case: An Al Qaeda Job Application" -- story from ABC News.
And here is a pdf of the full application in Arabic, with English translation.

What about the real qualifications required for a successful militant of Islam ....such as arson, loot, rape, hatred...
What about practical experience, such as infidels killed if any, raped if any, etc.
After all, carpentry is a profession of peace and not hatred, and as usual, Islam is turning good people bad.
Upon acceptance on must reply with the Islamic oath:
"Take me, I am a slave."
I believe I also found this application on Monster.com. Just search under "Jihadist" which is listed after "Janitor." Although I heard that their affirmative action plan leaves a little to be desired.
Did he have to supply a referance from the street gang?
"In the name of allah, most merciful, most compassionate"
These are the literal words that the muslims utter while sawing off the head of a goat/sheep/cow/camel.
It's good to see we have the documents. We probably have other documents.
Hmmm, I thought personnel records were confidential?
They'll probably try to sue in American courts; perhaps the 9th Circuit is their best bet.
Application?
Al Qaeda (Kayda?) is concerned with their employee's wellbeing; there is a place for emergency contact. They are interested in history of illness for insurance purposes (pre-existing conditions).
Who is the insurance provider? Now much vacation do new employees get? What is the beginning pay rate. Which act earns the larger bonus, killing a Jew or killing a Christian?
Are they covered by Workmen's Compensation when working in the US? Where's the W4 form?
There is a place on the form to indicate the number of children. I presume Al Qeda Inc. provides day-care.
Q. How could you be contacted in Afghanistan?
A. And my number is Beechwood 4-5789.
A. Pennsylvania 6-5000
An application for Al Qeda.? Keeping records is the prime source of evidence. A prospective mafioso never, ever filled out an application.