give source code for simaltaeneous access in vb.net

Question

I am doing my project in asp.net . My proj is online test. In this proj user may create a account and logon to proj then view the question and select the answer.User id is create in the server side. with the process of First come First serve(Eg.I connect my 5 lap in router as a clients and 1 server machine which means database. Now all the 5 clients create the account at simantaesouly but all user got the same userid if they entered at the same time.But if each client can create account in different time they got the correct user id of(user id 1,2,3,4,5).So give source code for this concept.)