Thanks all. That answers my question. Although the basic Kindle is not expensive, I didn't want to spend even a little money and have something that was of no use to me. I don't need to make notes, only read the files. The Amazon explanation does not spell out in plain language that files can be loaded directly from my computer
Thank you.
My recollection is that it's explained how to do so in the Users Guide, which is available as a PDF.
BUT, honestly. . .it's easier to send them. Unless you NEED them in txt format and can't work with the conversion. If you send them to the Kindle via Amazon, they will also then be archived there and available to be easily sent on to any other Kindle or Kindle app device that you may later get.
If you send them via WiFi it's completely free, though there is a small charge if you send them and they're delivered via 3G. To avoid the charge, use the 'send to' address with @free.kindle.com and it will only go via WiFi.
There's also a place in the "Manage Your Kindle" section of Amazon, to set it so that they are not allowed to charge you even if you use the regular @kindle.com address which means it will only ever be delivered via WiFi and you won't even accidentally be charged.