I followed this instuctions:
Step 3: Allow Multisite
To enable the Network menu item, you must first define multisite in the wp-config.php file.
Open up wp-config.php and add this line above where it says /* That's all, stop editing! Happy blogging. */:
So far, so good. But in my settings menu doesn't appear 'Network'. Ani ideas on what went wrong? Thank you!