You can refer to a cell in the A1 reference style by using the Range or Cells property.
This example demonstrates how to reference a single cell.
[C#]
//variant 1
book.Worksheets[1].Range["B3"].Value = 100;
//variant 2
book.Worksheets[1].Range["B3:B3"].Value = 100;
//variant 3
book.Worksheets[1].Range["B3","B3"].Value = 100;
//variant 4
book.Worksheets[1].Cells["B3"].Value = 100;
//variant 5
book.Worksheets[1].Cells["B3:B3"].Value = 100;
//variant 6
book.Worksheets[1].Cells["B3","B3"].Value = 100;
[Visual Basic]
'variant 1
book.Worksheets(1).Range("B3").Value = 100
'variant 2
book.Worksheets(1).Range("B3:B3").Value = 100
'variant 3
book.Worksheets(1).Range("B3","B3").Value = 100
'variant 4
book.Worksheets(1).Cells("B3").Value = 100
'variant 5
book.Worksheets(1).Cells("B3:B3").Value = 100
'variant 6
book.Worksheets(1).Cells("B3","B3").Value = 100
[C++]
//variant 1
book->Worksheets->Item[1]->Range->Item[S"B3"]->Value = 100;
//variant 2
book->Worksheets->Item[1]->Range->Item[S"B3:B3"]->Value = 100;
//variant 3
book->Worksheets->Item[1]->Range->Item[S"B3",S"B3"]->Value = 100;
//variant 4
book->Worksheets->Item[1]->Cells->Item[S"B3"]->Value = 100;
//variant 5
book->Worksheets->Item[1]->Cells->Item[S"B3:B3"]->Value = 100;
//variant 6
book->Worksheets->Item[1]->Cells->Item[S"B3",S"B3"]->Value = 100;