I need
to incorporate a message box into one of my "if
statements".

Well, i do not really understand the point.
do you want to test the result of the button clicked ?

Because if the problem is just to open a box under conditions it's easy:

if (condition) then
msgbox "condition true"
end if

else, the msgbox can be read
result = msgbox ( "yes or no ?", vbYesNo)
msgbox result

and the help of msgbox will give you all the possible values (vbYes or vbNo
for example)