Q: How do I add thumbnails to my posts?
A: Starting from 1.4, the recommended method to set your thumbnails is to go to the edit page of the post you wish to add thumbnails on, find the box named Post Thumbnail (probably located at the bottom right) and click on Set Thumbnail. Upload and select your thumbnail in the pop-up box, and you are done!
Q: The thumbnail sizes in my blog are too large. How do I fix that?
A: When WordPress does not have a thumbnail at a size that is needed (usually caused when the thumbnail size setting is changed), it displays the full image instead. You can regenerate your thumbnails by checking on the option below.