STEP 1: GET DOG INTERESTED IN TOY
The easiest way to get the dog interested in a toy is to slowly
move it around while encouraging him to grab it. The moment he
grabs it pull it around and move it a bit, basically play with the
toy and him.
STEP 2: CLICK FOR GETTING A TOY
Once you can get to grab a moving toy try requesting him to grab
it while it is not moving by just showing him, the moment he grabs
the toy click and treat him.
STEP 3: INCREASE HOLDING TIME
Once you can get him reliably to grab a toy, gradually increase
the amount he needs to hold it in his mouth before getting a click
and a treat.
STEP 4: MOVE AWAY FROM THEM
Throw a toy near you then when a dog grabs it start running
backward away from the dog while encouraging him to follow you.
The distance he needs to pass before you click and treat should
also be gradually increased.
STEP 5: FETCH
At this point, the dog should be able to bring a toy when you
throw it to him. It is a good exercise for the dog and a fun time
for both of you, keep playing with him and enjoy your game :). You
can always pull the toy when he brings it to you which keeps
things interesting for both you and the dog.