https://tinypng.com/ will reduce file size, though in my experience that still wasn't enough for the 100kb limit. After that you can resize it using Photos on Windows until it's under 100kb. That's all for using the thumbnails which in reality kinda suck unless you're posting tons of pictures.
https://www.uer.ca...d=1&threadid=60002 Go to section 7.3 for a guide on using flickr, it's just better. There's no file size limit, the pictures look better, and you don't need to scroll over every picture to see them. Hope any of that helps!