I’ve got this web designer doing my site and she is having me do the resizing.
Fine but let’s start with the landscapes – They all need to be 543 x 395. (to fit inside the image box) But when I change the width to 543 the height goes to 362. (which is the natural size). She said something about cropping? (But I don’t want to lose or change the composition unless extremely minimal)

&/Or What about shrinking it down to get this size from it being larger -is that transform? which I suppose also involves cropping. (if so how) I’m confused. It’s kinda mathematical – I can’t pre-figure it out so it downsizes to these exact measurements and without distortion.

How do I do this? Step by step? Is there a tutorial (Mac & PS C2) somewhere to spell it out for me. Thanks!

I'm not at a PC with PS on it right now, so going off memory here.
Open the image.
Select the Crop tool.
In the options bar up top, set the appropriate dimensions, but leave the resolution box empty.
Drag the crop tool over the image, resize and reposition as necessary.
Press enter to accept.

You'll also want to play with either the quality when you save or change the image size so that the resulting file size is reasonable for web use.

Hope this helps, and hope I got it right from memory.

Klassylass,
Unfortunately you can't have your cake and eat it to

You either need to figure out if you are going to scale for a pre determined height or width and then use image size to target that size. If you try to scale the width and height to fit a pre determined size it will stretch your image and most likely look horrible.

The only other way to do what you are trying to do is to is exactly what David suggested and use the crop tool to crop your image to the size you need but you'll have to sacrafice something in the process, either part of the image or the format etc...

Sorry I couldn't give you the answer you wanted to hear

Cris...