Texbox help

I need the code to use for a VBA textbox in excel.
1. I want to scan a UPC code into a textbox then write the data to cell "a5"
2. next enter a qty on hand into another text box and write this data to cell "b5"
3. next repeat step 1- except write the UPC to the next available cell in column "A"
4. next repeat step 2- except write the UPC to the next available cell in column "B"
then continue the loop

I have the text form created and I can use this code to insert into 1 cell, but I need to enter the data and then when run the same form enter the data into the next available empty cell in the column.

I have attached the excel file I am using.

Thanks for any help I might receive.

AttachmentSize
enter inventory.xlsx11.83 KB