Having a part cut from Solidworks is very easy.
Open the part
We start in an assmebly. Right click on the desired part and choose 'Open Part'
You are now in the Part editor:
Export to DXF
Right click on the part plane and choose 'Export to DXF/DWG'
Choose a folder and file name
Make sure the correct plane (Face) is selected at 'Entities To Export' and click on the green check mark
Make sure all desired lines are in the preview and click 'Save'
You can immediately upload the DXF file you just exported for ordering.