How do you know if a fuse has gone will it be burnt or something and also where are the switches in a peugeot 106 xn grad 1994 as one of my reversing lights has dont work and its a new bulb?

fuses are located in rear of glove box ,remove appropriate fuse ,or check each one if youre not sure, but only remove one at atime and replace it before removing another. fuses have two flat pin connectors connected to each other inside the see thru fuse body. if fuse has blown the metal connection will be broken inside ,easy to see , replace fuse with one of the same rating as on fuse body i.e. 5,10,15 ,20 etc. . dont know about switches yet .