ContourPlot3D[z==4 - (x^2)- (y^2),{x,-2,2},{y,-2,2},{z,0,4},ContourStyle->{Opacity[0.3]},Mesh->False, Boxed->False]

ContourPlot3D[{z==4 - (x^2)- (y^2),z==3,z==0},{x,-2,2},{y,-2,2},{z,0,4},ContourStyle->{{LightGray,Opacity[0.5]},{LightGreen,Opacity[0.3]},{LightGray,Opacity[0.05]}},Mesh->False, Boxed->False]

para=ContourPlot3D[{z==4 - (x^2)- (y^2),z==3,z==0},{x,-2,2},{y,-2,2},{z,0,4},ContourStyle->{{LightGray,Opacity[0.5]},{LightGreen,Opacity[0.3]},{LightGray,Opacity[0.05]}},MeshFunctions->(((#1)^2)+((#2)^2)&),Mesh->{{1}},MeshStyle->{Dashed,Black,Thick}, Boxed->False]

eixos=Graphics3D[{Thick,Blue,Arrow[{{{0,0,0},{0,0,4.4}},{{0,0,0},{0,2.4,0}},{{0,0,0},{2.4,0,0}}}]}];

Show[eixos,para,Boxed->False]