Apply format to whole column depending on row 1 contents

This is what I want the script to do, but how do I write it?

' ===============================>
Look through ActiveSheet.UsedRange

if <the first cell in column> contains (text1, text2 or text3)
whole column
width: auto
top cell only in column
text direction: horizontal
text align: h-left, v-bottom
rest of cells in column
text direction: horizontal
text align: h-left, v-middle

if <the first cell in column> contains anything else
whole column
width: 4
top cell only in column
text direction: vertical
text align: h-center, v-bottom
rest of cells in column
text direction: horizontal
text align: h-right, v-middle

move to next column and repeat until reached the end of
ActiveSheet.UsedRange
' <===============================

Hope this is clear!

Kind Regards,
Samuel Harmer