-Awesomely late reply-
In order to be able to use summoning you need to form a contract with a certain animal race, forming a contract is usually done by signing your name in a scroll using your own blood as ink. After signing a contract you're able to summon any summoning animal from whichever race(s) you've signed a contract which is usually done by first biting your own thumb to draw out some blood and then weave a few handseals and proceed with slamming your hand down, summoning the animal. Each animal has their own type of ability/fighting style and summoning races each have a unique home where they live such as Mt Myoboku for the toads.
Yeah, that's pretty much the best I can think of from the top of my head without using any source u-u