Go to a car spares shop (i think you have AutoZone?), buy some gasket material. Trace the shape of the flange on the gasket material and using a small hobby knife, cut out the exhaust hole and bolt holes. Using some permatex gasket maker and coat both sides of your new gasket. Install, nuts on exhaust studs, and ride!
Sheet metal gaskets
If your going to make them out of aluminium/copper sheet then the way i did it was to use engineers blue to paint over it, then put the flange on top of the sheet and measure the diameters for the holes, next using a compass, scribe the circles on to the sheet. I know that the bolt holes are 6mm but not sure about the exhaust port. If you dont have engineers blue then just use a pencil, next drill out the holes, I used different size bits for each hole. The exhaust port hole might be difficult so maybe use a smaller bit and drill a few holes in the gap then file the edges to give you the right shape.
Then I would suggest using some gasket sealant, put some on either side of your gasket, then put the gasket on (between exhaust pipe and engine) and allow the sealant to properly harden before you ride it, about 5 hours should be plenty. I was using a copper sheet gasket and to be honest it isnt that good at all compared to one made from proper gasket material.