There are several options for getting your images to display just right.
By far, the best option is to use your client image software installed on your local computer. This allows you to crop the image so it only has the area important to you. You can also use your software to resize the image. Images on your website will usually have a width of 600 pixels or less.
Another option is to upload the picture to SpinSite as it is. Once uploaded you have an option to resize the image. This option will physically resize the image on the server. By doing this you can make your images smaller so they'll download faster and display better.
Finally, you may simply scale the image by choosing a display size on the actual Image feature. When adding or modifying your feature with an image, try setting the image size. This will take large images and display them in smaller areas.
Note that if your image is a .gif you won't have the option to physically resize the image. You can still scale it in the feature options.