Use the Rows property to work with rows. This property return a Range object that represents rows of range.
In the following example, Rows[1] returns row one of used range on Sheet1.
Workbook.Sheets[1].UsedRange.Rows[1].Font.Bold := true;
The following example clears contents of row three in the range B5:F19.
Workbook.Sheets[1].Range['B5','F19'].Rows[3].ClearContents;
The following example merges the first row of range B2:C5.
Workbook.Sheets[1].RCRange[2, 2, 5, 3].Rows[1].Merge(False);