update Custom List field value based on other list value

Hello 

I need help form you ..I am new to sharepoint.

I had new sharepoint custom lists.

1. Issues and receipts ( item wise )

2.Stock details(Item Wise)

I want to update my2nd list whenever there is entry in 1st list.

I need maintain my stock details on day to day basis.

Pls help out Thanks in advance.