Data Structure basically is how you store data in a computer's memory. Variables are the first thing that comes to mind thinking of storing data. For larger data you use arrays. Then there's lists- Linked Lists, ArrayLists and all. Advanced data structures include Stacks, Queues, Maps, Graphs and others. You decide which data structure is best for your algorithm. That's the basic idea. Read a book on the subject. You'll have a more clear idea.