The software/system I and many others use is called ‘shrinkpic’ Just type that into your search box, hit enter. Go to their website, save it as a favorite for next time. Follow the on screen instructions, its quite easy really.
I find the easy way is to set your camera to the lowest or email photo settings. and upload strait from the SD card. I have and old and a newer camera and they both work this way. I had to resize photos on the old sit with Office picture manager but I think the new site will upload a larger photo.
File size is limited to 3072KB, this applies to photo’s, word documents and pdf documents.
There are a number of ways to reduce file size but I have found the easiest by far is to use shrinkpic. This runs in the background and automatically resizes photos when uploading to web or e mail attachment.