You can invite friends from the "Games" section. To access, select the option that you will see at the bottom of your home screen represented by a list icon.
When you do this, you will see the option "Invite friends" in the upper left corner and you must click on the "Go" button. Once you do, a new window will be displayed in which you can select between the different options to send a link to your friends, depending on the applications you have installed on your device.