how do I get an apple Id for the first time for my Iphone 8+?

You used an ID to sign into the support community.

See the Apple Support article(s) below.

Apple ID - create a new.      

Apple ID – Create        

Apple ID - Could Not Create or Could Not Set Up iCloud message.    

You enter your Apple ID choice and the related password choice when you Set up your iPhone, iPad, or iPod touch https://support.apple.com/en-us/HT202033