How to Add Post Thumbnails to Your Posts
Your Solostream theme will automatically display post thumbnails for each post unless you deactivate this feature on the Theme Settings page under “Basic Site Settings.”
Regular Thumbnail and Wide Thumbnail
There are two different thumbnails used in the theme. There is a standard thumbnail, which is 150px by 150px. There is also a wide-thumbnail, which is 630px by 315px. You can see the wide-thumbnails used on this page.
Note 1: for best results, ensure that your original images are at least 630px by 315px. WordPress can crop larger images down to size, but it will not enlarge images that are smaller than 630px by 315px.
How the Theme Sources Thumbnail Images
1. First, the theme will look for a thumbnail (or wide-thumbnail) image that you’ve assigned by custom field. You would use “thumbnail” and “wide-thumbnail” as the custom field names.
2. If no image is assigned by custom field, it will check for an image defined as the “Featured Image” on the Add Post screen (WordPresss 2.9+ feature). If you do not see the Featured Image metabox on the Add Post/Page screen, click the “Screen Options” tab in the upper right corner and select it from the list of options.
Note 2: You should always use the Featured Image metabox. This is the best method for assigning thumbnail images and featured article images.
3. If no image is assigned by custom field or the Featured Image metabox, the theme will look for an image that you’ve uploaded to the post. If you’ve uploaded multiple images to your post, it will use the #1 image as set in the gallery section of your media uploader (click thumbnail to the right).
4. If no image is attached, it will extract an image that you inserted into your post content.
5. Finally, if no image is found via any of those methods, a default image will be displayed unless you deactivate that function on the Theme Settings page.