I am considering embarking upon a Sten build.  I am however, unsure of the exact way to convert it to closed bolt.  Does anyone know of somewhere i could find some more info on this?

Never built a sten but I had looked here.

There is a very knowledgeable Sten group at yahoo, but, they can be very crusty and mean.

If you are looking at building from a kit, the only options used to be the SAS-3 kit, and the kit from Indianapolis Ordnance (link above). SAS-3 kits had issues, and I know they were not being made for awhile, not sure what the status is now.
If you are basing the build on a MK.II or MK.V there are other resources out there, but you will have to fire up your search-fu. There was one or two sites that had Sten forums, weaponeer being one of them, but I have not visited them for
quite some time. I posted a few WTB ads for SAS-3 kits, but since they are no longer in production, they are being treated as if they are made from solid gold. I have an SAS-3 Tube with template, so one of these days I may look into locating
the innards that go with it and try from there. Good Luck!