What package of files did you upload? You should upload the ms sql release files not source code. If you uploaded the source code I would delete all of it and then start over with the correct files.
DotNetOpenId.dll does exist in the /bin folder of the release files.
If you did upload the correct files, then its likely you are hosted in a medium trust environment, in which case you should see the notes here and adjust your configuration accordingly:
Hope it helps,