enter data in sql by time duration

Question

Hello to all,

 

I am beginner dotnet developer using c#.

 

i create a website in the i am getting issue.

 

question - 

 

when user login there account, he/she can register 2 more user on portal with there reference id and main user get points for that but it should be add both in 12 hour. if he add only 1 user then no point in 12 hour and other user in 2nd 12 hours. 

 

how can i do this in asp.net c#?

 

Please help & thanks in advance.