Jake, I know how to find out the size AFTER I have saved it, but what I don't know is how to determine the size in bytes at the time I am sizing it in Photoshop. All I see in Photoshop is pixels. How do I figure out how many bytes?

And why can't I figure out how to ask the right questions?

I have read my Photoshop manual, and all it says on this subject is that, "The file size of a digital image is measured in kilobytes or megabytes and is proportional to the total number of pixels in the image." The more pixels per size, the bigger the file. Of course! But where do I find how this translates into bytes without saving it and then going to Explore and checking the details on that file and then going back again to Photoshop and making an adjustment and then doing that whole process all over again?

Is my problem overly simplistic for all of you who already understand how to do all this stuff on computers?

Maybe I should just ask it this way:
If you are going to use a picture from one of your in-computer files, not on a website or anything, and you want to make it the maximum possible size as an ATTACHMENT to a post, do you save it as a .jpg file, and what resolution setting do you use and what pixel sizes do you use?

I am REALLY sorry to be so stupid about this, but it is important that I learn how to do this because I have probably more sailing photos in my files than almost anybody, and it would be nice to be able to share them once in a while.