The top section of these pages is usually styled with a large picture on the left with some text to the right. Beneath this in the main body of the page, there is usually a small thumbnail picture and some text to the right with a title above.
These are similar to the home pages in the top section but the main body tends to be more text focused with pictures to illustrate the article.
Top section pictures - 350x250 px works well.
Exceeding 350px may break the layout. If a wider picture is desired, for example stretching across width of top section then delete content of "image teaser", this will allow "quote & summary" to become left aligned. Then insert wider picture into "quote" section.
Thumbnails - 150x100px works well.
Main article pictures - 250px. This makes a reasonably medium sized picture in your main body text.
The space for the leaderboard is: 560 x 70 px. However, a standard banner size is 468 x 60 so you may find advertisers prefer to give you creatives in that size. The standard banner will fit well into the leaderboard space.
NB, advertising creatives (graphics) are best delivered in .png, .gif or .jpg.