How to add entry in the list for drop down in excel?

[Drop down list in Excel sheet]

I want to create drop down list for a column in excel.
I add one entry in the list, but it does not allow me to add second entry in
the list.

 

[Max]

I want to create drop down list for a column in excel.
I add one entry in the list, but it does not allow me to add second entry in
the list.

DV,
Suggest you start here at Debra's page:
http://www.contextures.com/xlDataVal01.html