Installing cia on sysnand

I heard that in order to make the blue gateway card work I have to install the cia file on my sysnand and I have no idea how to do it
I have hombrew channel access old 3ds xl 9.2 with gateway emunand 10.3
thanks !
Can you please share a tutorial ? because ever since I bought the gateway I'm not very familiar with anything non related to the gateway lol