You Probably need to resize the images to less than 300kb the eisiest option I found was to use paint as follows
1 open image in paint & save as to a location of ur choice lets say desktop for now
2 click image then click sketch & skew
3 now change the % percentage to 80%
4 click save
5 Now go to desktop & hover mouse over file & the details will show if it shows 300kb or less then you are ready to post
otherwise repeat 3
or if you still have paint open click undo & then repeat 3
Hope this hepls................