Conditional If statement to set cells equal to 0 - excel

Question

I have a spreadsheet that is over 6000 rows and 300 columns. I need to know how to write code in vba that will allow me to read cells in a column and if says "no" then it sets the 3 cells to the right of it equal to zero. There is no error when I debug it, but the error is in the cell.Offset line. Thoughts?
Thank you in advance
Sub Macro1()
Dim rng As Range
Dim cell As Object
With Sheets("Sheet1")
Set rng = .Range("C1:C6000")
For Each cell In rng
If cell.Value = "no" Then
cell.Offset(0, 1).Value = 0
Exit For
End If
Next
End With
End Sub

Answer 1

Borrowing chuff's code:
Sub SetTo0IfNo()
Dim rng As Range
Dim lastRow As Long
Dim cell As Range
With Sheets("Sheet1")
lastRow = .Range("A" & .Rows.Count).End(xlUp).Row
Set rng = .Range("A1:A" & lastRow)
For Each cell In rng
If cell.Value = "no" Then
'cell.Offset(0, 3).Value = 0
cell.Range("B1:D1").Value = 0
End If
Next
End With
End Sub

Answer 2

The following code should do the job. Using a For/Next loop, it reads each of the cells in Sheet 1 from A1 to the last cell in column A that has data. If the current cell has a value of "no", then it sets the value of the cell three columns to the right to the value 0.
Sub SetTo0IfNo()
Dim rng As Range
Dim lastRow As Long
Dim cell As Variant
    Application.Calculation = xlCalculationManual
    Application.ScreenUpdating = False
With Sheets("Sheet1")
lastRow = .Range("A" & .Rows.Count).End(xlUp).Row
Set rng = .Range("A1:A" & lastRow)
For Each cell In rng
If cell.Value = "no" Then
cell.Offset(0, 3).Value = 0
End If
Next
End With
Application.ScreenUpdating = True
Application.Calculation = xlCalculationAutomatic
End Sub
To set a range of cells to the right of the column A cells to 0, you would use slightly different syntax that still relies on the offset function. For example, to set the three cells immediately to right to 0, replace the above code line cell.Offset(0,3).Value = 0 with the following code.
Range(cell.Offset(0, 1), cell.Offset(0, 3)).Value = 0
This approach is necessary because, unlike the worksheet OFFSET function which can return a reference to a range of cells, the VBA OFFSET can refer only to a single cell.