In short when I select Auto from combo box I need the values(which are in column D in excel) in text Box

Hi, I just need code that I have 4 column A B C D in Ms-Excel In VB Form I had list first 2 columns value in Combo Box & 3rd column is also combo Box containing “Auto & Manual” 4th column is sum of column A & B In VB form there is Text Box in which the Answer or the Sum “column D” must be shown But I don’nt know what code use for Text box or Auto Manual combo box to display column D in Text box Thanks & regards: Muhammad Ata-ul-haq Sultani