depends on the laptops. some laptops you need to remove the keyboard (unscrew all screws - there is most likely some hidden under the stickers and rubber feet) then any internal boards that are in the way (this is a pain as laptops are the sort of thing that never goes back together again properley)

other laptops simply require you to pull a lever to get the drive out (thinkpads are liek this, so that you can easialy change between optical drive and extra battery)

some laptops you can just pull the keyboard out, some others you need to remove the fn key to get at a screw, while others you need to take out some screws on the base.

Thats why it would be useful to get that sony manual (google your model number and dissembley, theresd bound to be a pdf somewhere)

e.g on my thinkpad on the bottom there are screws, some hold the case together and others hold the keyboard on from underneath (those ones have arrows next to them) and are mainly hidden under the windows sticker and the small rubber feet