need to save some e mails but my high water mark is on how do i have e mails

You can save iCloud emails to your computer by creating a new Mailbox in Apple Mail, making sure that it is under 'On My Mac'. If you then drag messages from the iCloud mailbox to the new mailbox they will be downloaded and removed from the server. Don't try to do too many at once, and if you have a lot expect it to take quite some time.