When laying your copper tape at the start and end of each loop you need to leave a gap that will be slightly longer than the longest set of car braids.
Cut a slot in to the side of the slot in each loop. It needs to be in a fairly straight part but not to near the end of the loop if placed on the outside. If on the inside you don't need to worry so much about choosing a straight part. Install the micro switch and bend/adjust the leaver so to is across the slot and when a car passes it clears the slot and operates the switch. Repeat this for the other loop.
Start the wiring with the hardest part which is the main slot. Take the lead that would normally run to your track, from whatever power base you use, and connect the two wires to the moving contacts on the relay. The wires can either run direct or go through a connect block, the best option. Solder a jumper wire between one NC(1) contact and the other NO(2) contact. Then repeat this from the NO(1) contact to the other NC(2) contact. Then run wires from one set of NC and NO contact to the main track rails, it doesn't matter which way the wires are connected to the rails. Power up the track and make sure the wiring is working and the car runs, it doesn't matter which direction but make a note of which loop the car is running towards.
You now need to wire up the micro switches. Depending on the voltage rating of the relay coils you may be able to take power from the track power supply or you may need a separate power supply. Depending on the relay pins run a wire from the power supply to the coil common pin, if there are separate pins for each coil then add a jumper wire between the two coils and connect to one side of this. Now run a wire to common pin on each micro switch and then another wire from the pin that is live when switch is closed to the other coil pin on the relay and repeat for the other micro switch. Apply power to the relay coils and operate each switch, you should hear the relay operate each time.
The next two steps can be done direct from the power base, the connector if used or direct from the moving contacts on the relay. Assuming you have used a connector block, which makes things easier, connect two wires to the block. Run the wires to the rails of the loop that the car was running towards. Test the polarity of the loop with either a multi-meter or a car and make sure it is the same as the the main section. If it is the opposite switch the wires at the connector block. If the wiring is correct if you operate the switch in the non-wired loop you should be able to run the car along the main track and round the loop and then back up the main track. Yo can now wire up the other loop. Connect two more wires to the connector block and to the loop rails. Check the polarity is the same as the main rail when the car is running towards the loop, if not swop the wires at the connector block again. You can see why I said a connector block in the main powerbase to relay is the best option.
If all the connection are correct you should now have two powered loop and the main track should change running direction as the cars operate the micro switches. When you power the track up the best place to start a car is on one of the loops before the micro switch as this will make sure the main section has the correct polarity.