With Beethoven, 90% you should use the pedal to increase the amount of sound you get from the instrument. The other 10%, you can mess around with for effects. With passages with many notes that require a legato sound, try half-pedaling (depressing the pedal half-way, or even less, down). All the movements could definately use the sound you achieve by pedaling. Do not let any movement go without pedaling or the structure will fall apart. The whole sonata is basically one giant movement of a sonata almost. Listen to some recordings to get an idea too. Preferrably Brendel, but Richter isn't bad either. Hope this helps.