how does the automatic shifting work in a Hyundai Tucson 2005 it seems to work only in the manual position s
Not sure what you are asking . When you put it in D ( Drive ) you don’t need to do anything and the only way to select gears is in the Manual Shift position. Did you just get this thing ?
It should work like any other automatic, put it in Drive and the vehicle does the work. If it’s not shifting by itself take it to a good independent transmission shop. If you just bought it, as @VOLVO_V70 suggested, return it and either have the seller make it right or refund your money.
Section 2, page 8 of the Owner’s Manual explains how to control the transmission.