Hello Arun,
Just layed my first backers and you can get fitting techniques from the internet, it states that they have silica in them which is hazardous to health so use mask when cutting with knife. It also states that they are easy to cut and recommends using carbide tipped blade which i didn't have so used my normal blade and it took more than one score to get them to snap (quite a few actually). They sell screws specifically for backer with ribbed countersunks so they drive into boards but as i was laying 6mm onto 20mm floorboards and the crews were 30mm i had to draw line onto backer where the water pipes were running and use these screws where the pipes weren't and smaller zinc screws over pipes.
Using my wall trowel to lay i used up more addy than i thought but this was obviously down to floorboard height irregularities.
Still have little bit to go tomorrow but ones i have layed haven't cracked so far ( fingers crossed )
ATB Steve.