There are a number of ways you can obtain raster image files. If you have a scanner and scanner software, you can use the scanner to create raster image files. MapInfo Pro can read and display the raster image files created with the scanner software.
Some graphics software packages let you save or export images into raster file formats, such as TIFF (Tagged Image File Format). So if you can create a TIFF file with your draw or paint package, you can display it in MapInfo Pro.
You can also purchase raster images from MapInfo Pro or other commercial vendors. Some data vendors also offer scanning services.