How can I change the format of the excel which is being exported from the datatable?

I would like to change the format of the excel. Instead of exporting it like a datatable(refer to Fig 1), I would like to export like so.(refer to Fig 2)

Fig 1.
<Column1><Column2><Column3>
<Data1 ><Data1 ><Data1 >
<Data2 ><Data2 ><Data2 >
.
.
.

Fig 2.
<Column1.Data1>
<Column2.Data1>
<Column3.Data1>
-------------
<Column1.Data2>
<Column2.Data2>
<Column3.Data2>
.
.
.