I have to identify the orbit space of the action of the group $\mathbb{Z_2}$ on the torus $T^2=\left \{ (x,y,z)\in \mathbb{R}^3 |(2-\sqrt{x^2+y^2})^2+z^2 =1 \right \}$ generated by the homeomorphism $f(x,y,z)=(-x,-y,z)$
I think it isn't so hard, but i'm having some trouble understanding quotient spaces, and maybe this example would help me. Any hints?