Read what he said after the first line, it describes how to change your tileset and import images from other files in your tileset. There's another thing, however, called LVZ's, that allow you to put images of any size on the map. These can also be animated. Just download the latest beta version. Over the tileset, you'll see a "LVZ" tab, go there. Right-click in the area and add an image. There you can import an image in the LVZ library, and then you can select it like a tile, and draw with it. Note that these are just images, they are NOT tiles. If you want them to appear solid, you'll have to draw solid tiles under them.