There are 2 ribe ones at each end (the flywheel ones are quite hard to get at), 10 larger ribe ones front and back (5 each), the horizontal one that bolts through the driveshaft bracket, and two attaching it to the gearbox / rear engine mount.
The horizontal one is not captive, but once you've got it loose you should be able to get a finger to it to prevent the nut turning. It's even more of a PITA to get back on - I had to use a heavily-greased finger to stick the washer then the nut to to get it back on.
Once you've removed all the bolts, gently prise/knock the sump to unstick the instant gasket that seals it.
Then, once it's loose, it'll be stuck on the oil pick-up pipe. Remove the front bolt (11mm) and slacken the rear one until the pipe can swing forward and allow you to drop the sump completely.
Remember to drain the oil first as well.
If you've run the shells though, you'll need either a new crank or a regrind...