You have to use a decent graphics software program to reduce the size of your images. I use IrfanView which is free and does an excellent job of reducing images. You have to learn how to use the tools properly though.
Massdrive... to load a pic directly to your thread, while editing your thread there are toolbars above the text box you type in. On the right half of the toolbar there are some icons like a hashtag and a quote bubble. There is also a little picture icon with mountains and a sun, click this. To use this method, the pictures have to be remotely hosted and that host should give you a link to the picture in raw HTML. Copy this and insert it into the window that popped up when you clicked the picture icon. It will be text until you click the save button but when you load the regular page it should load from your remote host.