icloud refusing to work on my iMac

Hi there

I'm on a 2009 iMac running mavericks.

I recently acquired a new laptop running High Sierra and have the two-factor authentication activated.

I had to reset my password for my apple ID, but on trying to sign into iCloud on my system prefs I type the password and a dialog box pops up saying an Apple ID verification code is required. But there is no place for me to type in that verification code.

What do I do?