By recommendation do you mean types of RAM? Because pretty much any PC2-5300 SODIMM (the SODIMM means it fits the laptop ram slots) ram will fit in your notebook. The ram should be hidden under a panel somewhere on the bottom of your notebook. Switching out ram nowadays is pretty easy.
here is the memory specs for the Toshiba laptop you are looking for. it's portege M400.
-Configured with 512MB PC5300 DDR2 667MHz SDRAM (both memory slots are occupied)
-512MB (Min)/4096MB (Max), with 256MB, 512MB, 1024MB or 2048MB PC4200 or PC5300 DDR2 memory modules.