You have the ideal situation, a spare computer, of reasonable spec,
which you can devote to Linux.

Just boot up the CD, and select the 'Install' option. During the
installation you can select to use the whole disk.

Just follow the on-screen instructions. If mouse clicking doesn't work,
press enter, IIRC this was necessary at one point in the procedure.

You can vary the screen resolution & font size during installation
(sometimes the fonts can be rather small), but make sure that you don't
loose any boxes from the bottom of the screen :-)