I cant really figure out how to manipulate this spin button

I have a simple userform with a textbox and spin butto
The textbox displays the value that is found in column a in sheet 1

say there are 10 rows
row 1 value is "a"
row 2 value is "b" down to row value 10 is "j"

what I wan to achieve is to use the spin button where the and down button will display the next or previous cell value thats is displayed in the textbox.

for example if I write "f' in the textbox when I hit the up button it should display "g" or it will display "e" if I hit thr down button.

what Ive been doing is that when I put a value let us say c when i press the up or down button it will go back to a not yo d or b respectively. thank you in advance.