How can I resize pictures so that they are accepted as Attachments for posts on this site?

I assume you are on Windows platform.....right click on picture, Open with Paint, click on resize in upper panel, put in numbers compatible with site

Does anyone know
How to resize on an Iphone
What size

On a Windows computer download Windows Image Resizer

https://github.com/bricelam/ImageResizer/releases



iPhone:

https://www.imore.com/how-crop-resize-photos-your-iphone-and-ipad#resize