Well you'll have to check each cell otherwise you won't be able to detect a cell starting with 0.
try :-
dim lnX as long, rCell as range
lnx = row(Range("B" & activesheet.rows.count).end(xlup)
for each rcell in range("A2:B" & lnX)
if left(rcell.value,1) = "0" then rcell.value = "'" &...