You know the ranch in Paniola Town? There's a nursery there, with a girl and a miltank outside. You can leave two pokemon of the same breeding group there to make babies. You can check bulbapedia for the breeding groups, for example Kangaskhan is in the Monster egg group (http://bulbapedia.bulbagarden.net/wiki/Monster_(Egg_Group) ). The egg will be the same species as the mother.

You can also use a ditto to breed, in that case you can pretty much ignore the breeding groups and the egg will always be the species you are breeding your ditto with.

After leaving your happy couple to do their thing, run around in circles on your Tauros until the girl outside the nursery crosses her arms. That's her sign for "hey your egg is ready!". Go talk to her and pick up the egg. Run around in circles some more until the egg hatches. Keep checking if the girl has her arms crossed for eggs to keep a continuous breeding cycle.

To speed up hatching, you can use a pokemon with the ability Flame Body (Talonflame family, Magby family) in front of your party.

There are more things involved with breeding, but this is basically what you need to know to go ahead and experiment with it.

also what's shiny chaining ?

A different thing from breeding. You know when a pokemon calls for help? The point of SOS chaining is to keep knocking out the allies and make them call for help. The more help they call, the higher the chances of the pokemon that comes to help having a hidden ability, higher IVs and/or being shiny.

To breed shinies, use a pokemon from another region/language, it increases the chances of getting a shiny (masuda method). Usually people like using foreign dittos.