IPhone : Add vlaues in nsmutablearray's index which contains already data

currently I am facing a problem which is described below:-

I have a NSMutableArray. On its 0th index, there are some values. Now, I want to add more values at the 0th index of the same array. So, that I can populate all the data from 0th index itself. How can I achieve this?

I have tried by using inserObject:AtIndex: but this hasn't worked out. Any help will be appreciated.

Thanks in advance..!!