For a child aged 0 to 3 years old, it is best to use a Non-Flouride Toothpaste like the BURSTkids Strawberry Superstar, which can be picked up here
At this age, a child only needs a super light smear of Toothpaste roughly the size of a grain of rice.
For a child aged 3 to 5 years old, you can use the Flouride BURSTkids Toothpaste such as the Marshmallow Sparkle and Bubblegum Bonanza, they can be picked up here
At this age, a child needs a pea-size amount of BURSTkids Toothpaste to brush with. Once they are finished brushing be sure they spit out the Toothpaste.
If you have any queries then please do feel free to contact your dental professional :)