Config Lan2 in OpenWrt

good afternoon,
I would like to create a Lan2 and I need help since I can't do it without running out of internet.
My openwrt is installed on a Fritzbox 4040.
I have tried to create a new VLAN in the Switch tab but then I cannot configure it
If someone could help me

A proper solution will come with:

I don't know very well what I should do