Follow the following way:
Open Menu Bar –>Select System –>Select Preferences –>Click Network Connections
The following window will appear:
Select tab for ‘Mobile Broadband’ and click ‘Add’ button
Click the ‘Forward’ button
Choose your country and click ‘Forward’
Choose your network provider and click ‘Forward’
Choose your plan and click ‘Forward’
Confirm your settings
Most of the broadband connection uses the broadband number as username and password. But if you are having any confusion then contact your broadband service provider or may be its already in your broadband’s manual.
Fill in the details and click ‘Apply’
You may check the box ‘Connect automatically’ for making automatic connections. By checking this checkbox you will only need to plugin your broadband connection and it will connect automatically.