Janet & I have been comparing notes & I tested this on the app.
Members on computers must do their own image reduction to fit images within the site maximum. The app will do this automatically and reduce large images down to 600 x 800 pixels.
Janet saw a small arrow to click. My iPhone displays a + link -- or 'Advanced' depending on whether I have the screen in vertical or horizontal display.
A word about an Apple bug that Apple won't call a bug...
Images from iPhones or iPads sometimes show up sideways or upside in emails to friends. How to prevent -- look at your device when taking that picture. Turn your iPhone or iPad so that the camera lens is on the left as you take the picture. Like this --
That will assure that your image will display with the proper orientation. There is no installed software in an iPhone or iPad that can rotate and save the proper orientation. I'm sure there's an app for that.