Power Query-editor and i want to avoid using import mode

First of all, sorry for the bad english, not my first language.

I am very new to Power BI and I want to make a map that devides Denmark op into the regions. I was told to use Power Query-editor to get a column that says the name of the region, but i was told not to use import mode to help

I have used this to make sure that it will divide the regoins by using the postalcodes. the code I have come up with so far is this:

let changeZero = if [PostalCode] = "null" or [PostalCode] = null then "0" else [PostalCode],

postalCode = Number.FromText(changeZero)

in

if postalCode >= 1000 and postalCode <= 2999 then "Storkøbenhavn"

else if postalCode >= 3000 and postalCode <= 3699 then "Nordsjælland"

else if postalCode >= 4000 and postalCode <= 4999 then "Vest/sydsjælland"

else if postalCode >= 5000 and postalCode <= 5999 then "Fyn"

else if postalCode >= 6000 and postalCode <= 6799 then "Sønderjylland"

else if postalCode >= 6800 and postalCode <= 7699 then "Storkøbenhavn"

else if postalCode >= 7700 and postalCode <= 7999 then "Nordjylland"

else if postalCode >= 8000 and postalCode <= 8999 then "Østjylland"

else if postalCode >= 9000 and postalCode <= 9999 then "Nordjylland"

else "Ikke i Danmark"

Many thanks.