The code for the Wix YouTube video was already in the comments itself.
https://www.youtube.com/watch?v=MTBVyk0YGv0&feature=emb_title
As for doing this, you can go through the actual Wix tutorial here.
https://support.wix.com/en/article/corvid-tutorial-sending-tracking-and-analytics-events
https://www.wix.com/corvid/reference/wix-window.html#trackEvent
https://www.wix.com/corvid/reference/wix-window.trackingParameters.html#ClickProductEvent
https://www.wix.com/corvid/reference/wix-window.trackingParameters.html#CustomEvent
Or with GTM.
https://support.wix.com/en/article/tracking-click-events-with-google-tag-manager
There were previous forum posts that showed how to do this.
https://www.wix.com/corvid/forum/community-discussion/is-there-a-way-to-make-a-button-add-1-to-a-collection-field-everytime-its-pressed
https://www.wix.com/corvid/forum/community-discussion/increment-button-with-1
Finally, please add a new post if you require more help with your own issue, rather than bumping up an old thread from 2018.