You really shouldn't need to know the gmail settings; Thunderbird should be capable of finding them for itself.

File|New|Existing Mail Account will start the dialogue for adding an account.

I'd recommend you use IMAP with gmail. This and SMTP will use OAuth2 which works seamlessly. If you choose to use POP I think you'll have to set gmail to work with "less secure apps" and set up an application-specific password.

I thought when my PC was running Windows 7, that in t-bird I had one profile with its bunch of folders under my account (profile?) name And that when I rec'd an e-mail sent to my Cox & to my Gmail they both showed in the Inbox.

How I have this Windows 10 PC set up in that Cox is the only Account set up in T-bird. And that via the Gmail website have it set for copies sent to Cox with original set as read and with IMAP.

If you want to see messages sent to the gmail account in their own folders, you need to either set up the gmail account in Thunderbird, or set up filters in Thunderbird to move them from the cox account's inbox to what ever folders you want them to be in.

If you don't have the gmail account set up in Thunderbird, you won't be able to easily send messages using this gmail address as the "from:" address. You can probably make it work by some subterfuge. Or maybe you don't need or want to use this email address for sending?