Fritzing allows a designer, artist, researcher, or hobbyist to document their Arduino-based prototype and create a PCB layout for manufacturing. — Wikipedia – Fritzing
To produce Gerber files, first, open the fritzing project, switch to the PCB tab.
Now click right on the small drop down arrow (i.e. the small ▼ icon) at the right side of the Export for PCB button. Select File → Export → for Production → Extended Gerber (RS-274X) from the menu bar has the same effect.
Figure 1. Export Gerber button
A dialog will appear that asks you to select the folder to store the Gerber files. Browse to the place you want and click Select Folder button to confirm.
|Note||You can click the New folder button to create a target folder.|
Figure 2. Select folder
After you click the Select Folder button, all Gerber files and the drill file will be exported to the folder automatically. You can confirm this by openning this folder.
Figure 3. The exported files
Now you can open all files in a Gerber viewer (such as Gerbv) and inspect every layer, see if they match your design in Fritzing.
Figure 4. Check Gerbers in Gerbv
If everything is OK, zip the folder, upload it to PCBshare to place the order.
Figure 5. Preview of the board in PCBshare.com after uploading