The adjuster is in the solid mount at the 'other' end of the shoes from the wheel cylinder.
There is a square headed bolt on the outside of the backing plate. The inside of the bolt is a tapered 4 sided wedge. As this is screwed in forces out the two small followers and takes up the slack in the shoes. The bolt has a normal right hand thread so rotating it anti clockwise ( when viewed from the drive shaft side of the backing plate) will loosen off the adjustment.
Wind it out as far as it will go.
Fit the shoes and drum.
Centralise the shoes by pulling hard on the hand brake, and then release the hand brake..
Wind the adjuster clockwise, this will adjust the shoes outwards and bring them into contact with the drum. At the final part of the movement you will fel that the adjuster nut will alternativly tighten and loosen each for each
90 degrees of rotation.Correct adjustment is with the adjuster between two 'high points', and with the shoes not dragging on the drums.
Go for a short drive, stopping both going forward and reverse, make final adjustments.
Note that it is quite common for the adjusting bolt to be corroded and stiff to turn. I always remove the working parts and clean before replacing shoes.
Wiggle out the two followers, these are cylindrical, with a angled face at one end and a slot for the shoes at the other. Wind out the adjusting bolt. Turn clockwise ( when viewed from driveshaft) It will come out through the central hole in the middle of the adjuster body.
Clean and lightly smear with grease and reassemble.
Hope this helps
Ian F