How to use InStr function to search for a text that starts with "CTF" and ends with "."?

so what i really want to do is that if a user types CTF in the tb then whatever follows is searched in a range(a1:A20) and then it returns the value to anther tb named tb1 , now when i put a "." i want the range(ctf) to have the value which appears in the tb1. my main textbox is named notes

in short i want to trigger the following event if notes has a text that starts with CTF and ends with .

i want the value of range("CTF") to change to whatever appears in tb1

sort of like if instr(notes.text, "CTF" & * & ".") then
range(ctf).value= tb1.value
end if