How to pass dynamic column name for excel sheet in c#?

Question

 

Hi,
I have a excel sheet where my data populating from F column of excel sheet to anything.Anything means column F,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z,AA,AB,AC like this.
I am using below function to achieve this.
I want dynamic function where i passed F column name.

Public void Test1111()
{//Populating extra column of PlanProperties.
 Row contentHeaderForPlanProperties = CreateContentHeaderForPlanProperties(worksheet, rowCounter, "F", salesPlanProperty.FieldName);

  sheetData.AppendChild(contentHeaderForPlanProperties);

}
Instead of F i want dynamic function which count from F to  next onwards.
Thanks!!