Find Column Title instead of using Ranges

I have a Excel sheet with 3 columns, Start date (Column Title: Start), End date (Column Title: End) and Price (Column Title: Price).
My current macros is calculating the New Price (365 days) based on the Price given and the Start and End date. The current macros, I have inserted Column Ranges, but each time the the sheet will be different, so can someone help me to change this macros so that it work with multiple sheet where it finds the 3 different Column Titles first and then apply the formula and output New Price will be in the first blank column.

Sub NewPrice()

Dim TotalPr As Range
Dim StDate As Double
Dim EnDate As Double
Dim NewPr As Double
Dim Days As Integer
Dim Length As Integer

StDate = 0
EnDate = 0

Set TotalPr = Range("A1").End(xlToRight).Offset(0, 1)
TotalPr = "New Price"
Length = Range("A:A").Cells.SpecialCells(xlCellTypeConstants).Count


For j = 2 To Length

StDate = Range("B" & j)
EnDate = Range("C" & j)
Days = (EnDate - StDate)
NewPr = ((Range("D" & j) / Days) * 365)
Range("E" & j).Value = Newpr

Next j


End Sub