The Featured Links section can be edited by navigating to Content > Link Lists > "Featured Links".  This section can accept 1, 2, 3, or 4 links with images It is recommended that image sizes all be the same.  Reccomended image sizes are as follows:

4 Images: 220px by 131px

3 Images: 300px by 182px

2 Images: 461px wide, no more than 276px tall

1 Image: 942px wide, no more than 276px tall