This is pretty  simple, in a complex way, when you have your circuit designed, you might want to get it on a PCB and then solder components to it.  For instance the UNO board uses a type of chip that allows you to use a socket for the chip, or not.  So for instance you design a cool light control system for your bike, then for about $40 you could get the PCB built and then solder your own components to the board.  Not easy, but definitely better for the final product since the soldered components will adapt easier to the bike by  being smaller.

So if you use the Fritz approach, the Berlin company  will take your design and make a board.  See the link:

http://fab.fritzing.org/fritzing-fab

They  build the PCBs once a week, so if you submit by  May 20, 2014 you will get your circuit shipped on May  28, 2014.

That’s it.  But if you are going to be part of the Internet of Things, you will need to at least understand the process that is used to build a sensor from start to finish.  Remember that there will be a TRILLION sensors in the world by 2030, how old are you?  A US/UK Trillion is 1,000,000,000,000 things.  Elsewhere a Trillion might be the same or it could be 10,000,000,000,000, but either way  that is a lot of opportunity.