Open the Experience, click on the + button on the Summary tab at the bottom right of your screen.

Select People and then select Viewer.  Then choose how you will invite them (Connections, a Group, via Email, or with a Link).  Any Experience member can add Viewers to the Experience.  Viewers can view the Experience but not add any content.

Alternatively, you can click on the People tab and then click on the plus button.

This allows you to share your best times with family and friends even if they weren't there with you. 

Any Experiences that are shared with you and you are a Viewer appear on the timeline with a label "View-Only".