Via the Performances page of your Event and adding them to either individual or multiple performances using the Action bar.
Follow the steps below:
a) Go to your Event and click the Performances tab
b) Click the box next to the performances you want to link products to or find performances using the Filter bar
c) Select the Product icon on the Action Bar at the bottom
d) Select your Product from the pop-up list
e) Select Link to Performances or Link to Performances, with a stock level per performance and then enter the number
f) Click Submit
g) To see Linked performances, go back to Products and select your product
h) Select the Visibility tab and scroll down to Linked Performances