Information:
Blended familes are basically familes that have child/children from previous relationships and/or marriages. Having blended familes usually occur, when couples divorce from one another. The child would either end up with the mom or dad. Once, the divorce has happened, the mother or father will be able to be in the "dating world" again. So, if they happen to find another soulmate, then they'll eventually get married, and have kids. And, when the child from the previous relationship and/or marriage, gets a stepbrother or sister, this is the point where their familes become a blended family.
The paragraph above is just the genreal idea on what a blended family is. Blended families are very complicated, and can lead to very bad situations. Both parents have to work out some schedule for the child and/or children to vist their biological father or mother, and finances etc. There are tons of responsiblities that come when you have a blended family. You just have to make it work.