Forward Roll 
Basically if you are PUSHED from the back or 'on the back' 'projecting' forward.
-You slowly fold downwards and forwards ​as you step out with one leg (like a lunge) and then continue to a forward shoulder roll. 
-You can practice this from the Ground position (like a starting block position in a race , instead you just gentlly roll forward.
SELF DEFENCE SITUATION:
You are PUSHED FROM THE BACK and have to FALL FORWARD . (as simple as it sounds if you cannot do this or have not been shown HOW basically most people would fall 'face First' into the 'Pavement' and recieve serious facial injuries or reach forward with both hands and 'break both wrists' (I have seen this happen and it is so easy to sustain an injury for an 'untrained' person GH) 
 

 Backward Roll  
 here you are pushed from the Front and you have two choices :
1)Fall straight backwards and 'SMASH THE BACK OF YOUR HEAD ON THE PAVEMENT' which an untrained person will do because they do not know how to soften the fall or fall properly = serious injury to back of head (could easily be a fatal injury).
2)STEP BACK WITH ONE FOOT into a low squatted position while pointing(this keeps the line of focus) at the Attacker with one hand and index Finger (the other hand is at 90 degrees to the pointing one) while you Step back into a LOW ONE LEGGED SQUAT after this move (STAGE ONE) you simply roll backwards over Your Shoulder
(head tucked in)  complete in squatted position)  full 360 degree circle backwards and come back onto your feet (in a semi squatted position) facing the Attacker but about 1 to 2 body lengths away , ready to defend again.
Move (2) = NO INJURY and ability to Defend youself plus 'bonus' you have created 'Distance' between You and attacker.
 

Roll out of (over the shoulder wrist lock)
When an attacher places you in a wrist locking motion (by twisting you hand and wrist over your shoulder ) backwards locking out your wrist backwards (you either roll with the lock or get your wrist broken if the attacker keeps the pressure on the wrist) .
The COUNTER MOVE: you perform a one legged (russian squat) as the attacker twist you hand and wrist over your shoulder, You drop with the twist in the "circle" motion (the leg and hip on the same side as the wrist lock lowers down and you eventually roll onto your shoulder completing a "circular motion" and roll out of the lock.
 

Counter move and Break fall to Attachers (Over the Hip) Judo throw 
When The Attacker committs to a judo throw .
The Counter Move: You grab around the neck of the attacker , and perform the (Side break fall move) when you do the "drill" you imagine that you have "slipped on a Banana peel" with one foot (as that foot 'slips sidewars) you lower yourself down in a "one legged squat" and break the fall to your side of hip (hand face down and not a hard slapping motion but a 'soft slap' remember the surface will be concrete no a MAT !, so you soften everything down.
with the had that is holding on the attackers neck you pull him down with you , and if you have enough momemtum you can counter throw him away from you, (as you recover) or if you only have enough momentum to break your fall(and pulling him down) as your hand will be hooked over his neck , his face will be open to counter attack in this position . (see (e) Learning videos to clarify.
 

Rolling over an Obstical (Table ,fence etc) 
 

Healy's 'Drills' to learn the basics in 'HARD SURFACE' Break falls 
 

Sacrafice Throw (Attacker gets thrown into full body slam) 
 

Slip under and 'Wheel Roll' (counter to 'Over the neck' front 'bulldog' Choke Hold' by attacker