In Windows above Vista you need to open cmd with administrative priviledges: menu/cmd/right-click/open as admin
Create a user with a password and options:
net user username password /ADD /PASSWORDCHG:NO /EXPIRES:NEVER
Once created you can assign that user to a group:
net localgroup administrators username /ADD
Change a password:
net user username password
Change expires option:
net user username /EXPIRES:NEVER