How to automatically open post at page

How do I add a code snippet to my embedd service chat components? I found tons of resources that say I need to add a code snippet, but I am not sure how to do that.

i just need to add this bit of code.

https://developer.salesforce.com/docs/atlas.en-us.snapins_web_dev.meta/snapins_web_dev/snapins_web_postchat.htm