EDMX canvas and generating a database from Model question

I generated the database from the model now I notice that all the tables have an "s" appended to then Userid object transloated to Userids in SQL.

which nwhen I run the code

Userid userid = db.Userids.Find(id);

gives me this error: System.InvalidOperationException: 'The entity type Userid is not part of the model for the current context.'

is the "s" added at the end of all the tables correct?

THIS IS THE ACTUAL ERROR I GET

System.InvalidOperationException
  HResult=0x80131509
  Message=The entity type Userid is not part of the model for the current context.
  Source=<Cannot evaluate the exception source>
  StackTrace:
<Cannot evaluate the exception stack trace>