DSN With SQL 2008

Some one know how to make DSN with SQl 2008. I am getting error

4 answers

Can you connect to the server using management studio?

Is the server on a computer different from the application/website? If yes;
You need to verify that you can access the server over the network. What protocoll are you using for your dsn connection; named pipes or tcp/ip?
If tcp/ip; verify that you can connect using telnet; from command prompt enter "telnet myServerAddress 1433", there will be an error message if it cant connect, if it can connect there will be only a blank input screen (no "connection success message" or such).
If named pipes; try the above over port 445.
Hope this helps!