Howdy!
The error basically says that you're referring to something that doesn't exist. From your script, it looks like you're trying to fire a function called Round1()
but the server is saying such a function doesn't exist. You need to put the function above the trigger so that the server knows to look back onto what you're talking about.
If this helped you out, consider accepting this answer for those sweet, sweet reputation points. If not, comment below and I (or someone else) will help you out.
Be sure to check out the Roblox API Documentation as well for additional reference.