Mine is a Comcast email address.

If nothing else, call Apple. Their customer service is very good.

Since it's all I have?

You can get a gmail email address for free.

On gmail or yahoo. Then use that as your Apple ID.

I just want to use my desktop computer to look at my Icloud email because my phone is a crappy IPhone 6 and it's ancient but makes calls and texts and receives my Icloud emails.

I have a password that was created when I set up this Icloud email years ago. What good is it if I have to have some other ID anyway?

One will save your passwords behind a master password (don't forget it!), allowing you to use secure LONG passwords with alphanumerics, without the usual posit-notes all over the place.

If you manage to forget the master password, apps that I have used *do* allow you to export the password data to a file. Just hide the file on a memory card (or printout) that you can lock up.

I am currently using Samurai Safe on Mac and iOS. It's free. I dropped the other app when they (wouldn't you know it) went to a subscription model.

There are others, of course.

This doesn't answer your "email account" post.
I use a Comcast address in addition to iCloud.
Every Comcast account owner gets to create 6 of them, last time I checked, and you must know someone who uses Comcast.
Using an email address as primary ID is dumb. But big companies often do dumb things.

https://ntietz.com/blog/email-address-not-identifier/
Email addresses are not primary user identities

Sorry about that. I wouldn't use anything they provide any more than I would use Facebook or Twitter, which I don't.

I just thought that I could access my Icloud email on a device besides my decrepit phone.

I don't guess that's happening.

Correct me if I am wrong, anyone.
And check with an Apple support person.

If you have icloud email, you must have an iCloud ID.

On your phone, go to Settings -> Passwords
You will need your phone pass or touch or Face ID to see them

That will have your account and password info.

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As for Comcast, anything that someone paid for has a fighting chance of staying alive. Free accounts can and do vanish for no reason and it can take forever to find a real person to unlock an account. Two email accounts are a boon because one can go down at any time, even Apple's. With iOS you can set up fake accounts that forward to your real email ( "Hide my email" ) and that's handier than throwaway accounts (getnada.com and others) to deal with spammers.

You most likely already have an Apple ID and would not need to create a separate one for the desktop. You can find the Apple ID under “settings”. Should be the first item. If you don’t find it there, try googling “find apple id on iphone 6” for more tips, including screenshots.

Hope this helps.

Leading me to the Settings was the right place for me to look.
I do already have an Apple ID (I wouldn't have known this), and found it under Name, Phone Numbers, Email.
It lists my Apple ID as my iCloud email, and all I had to do was enter it, and my password (set up when my ex gave me the phone), and I was logged on to my account.

Thanks a whole bunch!

Kind of makes my day to know my brain can still pull up useful tidbits when needed

as a backup.

Took them about 10 minutes. Overall, I was pretty impressed with their support line.

hope they may be useful for you.

Set up iCloud Mail on all your devices
https://support.apple.com/guide/icloud/set-up-icloud-mail-mmdd8d1d47/icloud

System Requirements for iCloud
https://support.apple.com/en-us/HT204230

iCloud User Guide
https://support.apple.com/guide/icloud/apple-id-and-icloud-mm864f5e6593/1.0/icloud/1.0