Hola Martin!
Do you mean you would like to load the SeaWiFS image in "true color"? True color is the L1A browse product, and creates an image similar to what you would see if you were looking at the Earth with your own, human eyes. To load a true color image, you must first create the browse product using the "SeaDAS -> Process -> SeaWiFS -> browse" program (
http://seadas.gsfc.nasa.gov/doc/browse/browse.html). After you have created the browse product, use "Seadisp -> Load -> SeaWiFS" to load the true color image.
If this isn't what you are looking for, please provide me with some more details and I'll try to help...
¡chau! mike