Geometry preparation for Conjugate heat transfer simulation in Cubit for openFOAM

I am new in Coreform cubit and trying to create a geometry for chtMultiRegionFoam solver in openFOAM. The case setup will be followed by a heat generated cylinder surrounded by a fluid domain box. How can I create this geometry and set up the boundary conditions for the solver? If anyone could help me in this section then it will be great for me.
Thanks.
The geometry code is given below for cubit

(Non-Commercial License) Cubit>brick x 10

Successfully created brick volume 1

Finished Command: brick x 10

(Non-Commercial License) Cubit>create cylinder height 10 radius 2.5

Successfully created cylinder volume 2

Finished Command: create cylinder height 10 radius 2.5

I need to setup the case for chtMultiRegionFoam where the box will be worked as water domain and the cylinder will be worked as heat generator. How can I do that?