How do I make a folder for my mail?

Are you using Apple's Mail app? If so, in the Menu under Mailbox, select New Mailbox & name it. The new mail folder should appear on the left side with your other mail folders.

 Cheers, Tom 😉

Is it possible to make a folder and have designated emails sent to that folder? If so how?

No. Move them to the folder after they have appeared in your in-box.

Actually, it is possible.

Go to Mail menu>Preferences>Rules (far right tab). Click Add Rule and give it your criteria. When you close your new rule, it will ask if you want to apply the rule to the mail already in the box.

For a rule to work successfully, you need to be very specific. Look carefully at all the options and you should be able to see how to set it up to separate out the specific mail you want to file. If you have more than one email address, that needs to be part of your rule's selection process via "Account."

Also, make sure to correctly use the "If ALL/ANY of the following conditions are met." If you leave it with ANY, then no matter how many criteria you have, it will move mail with ANY of those criteria.