What are the basic steps to make a printed circuit board? I created a shield for Arduino on a soldering board. The next step shall be to implement the circuit on a PCB. I'm new to this, so I'd like to know what the basic steps in designing a PCB are. 

More specifically, 


What software do I use for this? Is free software sufficient, or do I get substantially more value from a commercial package? 
Can I have a single PCB printed by a commercial provider, or are there minimum quantities? What is the approximate cost for a shield-sized PCB in a small quantity - is it in the tens, or rather in the hundreds of bucks? 


Of course, any pointers to good tutorials on the Web will be appreciated,  too!
Software packages are, amongst others


Fritzing (more target at beginners)
Eagle (free for board of size 100 x 80 mm (4 x 3.2 inches)).
KiCad (open source)


Companies that make you pcb in small quantities are e.g.


OSHPark
seeedstudio
Dirt Cheap Dirty Boards


I personally create my own double layer PCBs at home. I first started with the toner-transfer method, but now use photo lithography. I etch in Hydrochloric acid and hydrogen-peroxide. I can have a finished board in 1-2 hours, instead of having to wait a week or so. Great learning experience.