today went to buy oscilloscope of 20 Mhz ...i will get it tomorrom..

i also went to see my friend who is studying in a electronics engineering university we tried to use the oscilloscope to see waves but the waves were not coming in a proper way...they were coming in ac format not in square waves but i will be doing this properly tomorrom...

i know this is out of way question but how should i use the scope for calculating the pulse width...