Mobile Number usertype the number start with 0 validate

Question

Mobile Number Textbox1
 
in that mobile number if user type the mobile number start with 0 and user does not type 10 digit mobile number completely.
 

1 st Example
 
Mobile Number 0
 
2nd example;
Mobile Number 9840567
 
that time user click the insert button i want to show the message"Enter Correct Mobile Number";
 
how to do in asp.net with c sharp .help me.