Explaining things, too be honest even trying to write things down is not one of my good points, so here we go.
Open your picture in microsoft paint, if you want to crop your photo, make sure you have the tab home selected, under the tab "view" is select, click on the box just above select, go to your photo and highlight what part of the photo you want then click on crop. Weather or not you crop your photo you then click on resize (under crop) type in say 10 then OK then save, check the size of the file, if under 200k you can then post.