This would return the left two characters of the old string:
newstring = left(oldstring, 2)
This would return the right two characters of the old string:
newstring = right(oldstring, 2)
This would allow you to start somewhere other than the left or right. For instance, the one below will start at character #2 and read 3 characters to the right of it.
newstring = mid(oldstring, 2, 3)
Hope this helps.
Shannan