Take the microSD card from the source system and insert it in the target system.
In order to take the microSD card out of the slot, push first so it pops out. Pulling it out with force may result in damaging the microSD card slot.
The data on the source system's microSD card will only be usable on the target system. After performing the system transfer, insert the microSD card from the source system into the target system. If you use the target system without inserting the microSD card, you may not have access to save data for certain software titles.
You will not be able to perform a system transfer if there is any Nintendo Network ID already linked to the target system.