The number of systems is not relevant as long as the current doesn't exceed the driving power of the Transistor.
In a series connection, as you show, the voltage (24 V) from the regulator will be divided among the elements. As shown with 5 elements in series each element will "see" only 25 V / 5 = 4.8 V. The current will fall to 1/5 of the current with a single element. If that is enough, the go ahead.
If, however, you need the 24 V, you need to put the elements in parallel. Now each element "sees" 24 V, but the current will rise to 5 times the current of a single element.
May I suggest that you start experimenting with the comparatively simple setup using only 1 element as discussed above before you start exploring alternatives and different setups? Make yourself acquainted with the functions of the different parts of the circuit. In my opinion it is also a good idea to buy a multimeter ( a cheap one in the $ 10 / € 10 range is sufficient). Thus you will be able to measure voltages and currents and get a better feeling what's going on. Obviously you lack the theoretical background so some measurements will help you get along better.