To set up tabbed browsing:

Choose Safari > Preferences.

Click Tabs.

Choose the settings you want. Click the Help (question mark) button to see an explanation of the options.
Tabbed browsing lets you view multiple webpages as a set of tabs within the Safari window. Some people are passionate about this feature. If you’re not sure, try it for yourself. You can always turn it off.
Choose Safari > Preferences.
Click Tabs.
Choose the settings you want. Click the Help (question mark) button to see an explanation of the options.