HOW TO CREATE BADI IN ECC 6.0 with Enhanance Spot?

HI,

Anyone let me know how to create BADI in ECC 6.0 , which have mandtory to create enhanance spot before to create badi? I dont understand the concept of Enhanance Spot and what is the purpose to create that . Will u plz let me know step wise procedure to create badi ...

Thanks,

saurin.