By default the remote MS-SQL server connection not enabled once you have installed in your system, We can enabled in few steps,

Step 1 : Go to Start  ->  Programs  ->  Microsoft SQL Server 2xxx   -> "SQL Server Configuration Manager"

Step 2 :  Then, Select "SQL Server Network Configuration" on Tree View left panel  You will see "Protocol for SQLEXPRESS"

Step 3: Double click on "Protocol for SQLEXPRESS"  You can see protocol name and the status (Enabled/Disabled)

Step 4 :
Right click on "TCP / IP" protocol and click on "Enabled" and go to "TCP/IP" properties. For example refer the below image.

Step 5 :  Scroll down to "IPAll" place  need to  sure TCP Dynamic Ports is blank also the TCP Port is set to 1433,

Step 6 : Fianlly Click on "OK" buttton.

Now, you can easily access your mssql database in your system from the Server.