Did you enable TCP/IP from Configuration manager? By default it is disabled and you need to enable it to connect from a remote client.
To enable TCP/IP:
1. run SQL Server Configuration manager
2. select SQL Server Network Configuration
3. select Protocols for ‘instancename’
4. right click on TCP/IP and select ‘enable’
Do you have Sql Server Management Studio. If yes, then you can open it and right click the instance in question, go to Properties -> Connections -> Check “Allow remote connections to this server”.
You might also have to enable TCP/IP Protocol to be enabled thru Configuration Manager.
