In order to insert a picture into a post, it must be within the stated limits, in terms of picture size (pixel x pixel) and file size (kb's)
picture size can't be wider than 640 pixels, and the height can't exeed 1500 pixels, the 1500 pixel figure allows for 2 or 3 pictures to be edited into one file.
The file size has a limit of 200kb
So, you probably need to use a photo edit piece of software, such as Adobe Photoshop (high end) or a more simple one such as Microsoft paint (part of windows) to reduce your pictures to within these limits.
Save pictures as .jpg's as they are the most commonly accepted.
"I Agree with everything you say really!" - John Cooke to Jon Fuller - 26-01-2013