Fruit Trees

Hya folks, need guidance badly.

Bought some so called dwarf fruit trees a couple of years ago,( can't remember where from)  Apple Braeburn - Plum Victoria -Cherry Stella -&  Pear Conference, which were planted in containers.

Didn't expect any fruit from the Plum ,Pear & Cherry for a year or so, even though they blossomed nicely, but last year the Apple bore some fruit which grew to about one inch diameter, then all fell off, this year the same thing is happening again, but with fewer fruit.

I have no idea how these trees should be pruned, could this mis-management be the cause of the failure?

T.I.A.

peterpiper