When I take my pics, I make a file for that date to keep them in.
Straight off the camera, my pics are 2.64MB and have dimensions of 6000 x 4000 - way too large to upload to this site.
SO I open my pics in Microsoft Office Picture Manager, press 'edit pictures' then 'resize'. I resize by 30% to bring the pic down to 1800 x 1200 pixels about 440KB.
Now you should beable to write a post then below the textbox you will see the upload attachment tab, press choose file and you locate the file you stored the pics in and away you go.