Make 1 hdd with multiple ones

Hi,
I have installed Fedora 29 2 weeks ago on one of my computer(1x 512GB SSD & 1x 1TO spin drive).
The installation took care of combining my 2 drives into 1 and it was FAST!
I’d like to install Ubuntu budgie with the same configuration…
Can someone help me please?
Any help will be much appreciated, thank you very much.