Apache POI—将数据插入到特定的列/行中，并显示EXCEL w/ Java

I have a document in excel that I want to edit or input a data on it using java..I have try it but all I can do is just delete the data in my excel and replace it the data which I just input.I'm using Netbeans for my compiler. My output is GUI/JFrame how to Insert data into a specific column, row and sheet?? example I want to insert it in C12, E11, Sheet1 etc.I have a document in excel that I want to edit