No bootable device

I am new in using a mac. I decided one day to try to run windows on my macbook pro osx lion. So i entered bootcamp assistant and selected that i had a disk or something with windows installation... I partioned the computer but i couldn't go to windows because i didn't have tgis disk... (ok i'm stupid). Then what i did is ejecting bootcamp from computer. When i restarted the mac, it told me " no bootable device -- insert boot disk and press any key". I have read that i could press the option button to run the mac but it's not working.
What can i do?help me please...
Sorry for the english

If you have Lion you should be able to restart in recovery mode, Restart and hold down the Command-R.

http://support.apple.com/kb/HT4718

Ok thx it works
My goal now is to remove the bootcamp.
Btw i don't have the create or remove option in the bootcamp assistant.
Do you have any idea?
Thank you very much

To remove a Partition you can use Disk Utility.

I know how to use disk utility to erease files on a disk but i don't know how to use it to remove a hole disk...

Select the Disk
Got to the Partition Tab
Select the correct partition and click the (-) minus button.

Will it give back space to my first disk?

Yes, its all very clever.

I don't have any partition tab

Select the Disk, not the Partition. The one with the supplier provided name.