How to add a second disk to shared space?

Question

I have two disks on my laptop (ASUS FX-505DT), which has two disks: SSD (256 Gb) and HDD (1 Tb). I installed Ubuntu 22.04 and can write only to disc with OS. But on my side panel i see icon of my HDD and can open it and read. How can i setup my system to write on it too?enter image description here