So what's going on and how does all this happen, what are the processes involved and how do Amateur Astronomer's make a contribution. All good questions!
Step 1 - Re-photograph the area and check for asteroids and or artifacts in your image
Step 2 - Check a previous known image of the same area and compare to make sure nothing was there before. You need to be careful doing this as different images may have different orientations depending on the Position Angle of the camera. It may be flipped horizonal and vertically to your image. One such site where you can do this is the CDS (Centre de Données astronomiques de Strasbourg) Portal which has a searchable web interface for various star Catalogs (just enter the exact RA and Dec).
Step 3 - Once you believe you have something - alert some of your collegues and get some confirmation images
Step 4 - Report to CBAT with the exact postion to the nearest arc-sec with an estimate of the magnitude and of course your location, telescope and discovery circumstances (eg PSN J09554214+6940260 where "Possible Super Nova" is RA is 09 55 42.14 and Dec +69 40 26.0).
Step 5 - Wait and hope you are the first in - but you'll have to be quick ;-) Its always a great idea to get someone to check your work so you avoid embarrassing mistakes.
Step 6 - Then sit back and wait for other astronomers with spectroscopic capabilities to confirm the Supernova type by assessing which Balmer Lines are present in the spectra.