Assuming you are trying to use PDE Toolbox, you can use the multicylinder function to create cylinder geometry and mesh as shown below.
R = 0.1;
H = 0.5;
gm = multicylinder(R,H);
% Assign it to a generic PDE model and plot the geometry.
model = createpde;
model.Geometry = gm;
figure
pdegplot(model,'FaceLabels','on')
%Generate mesh and plot the mesh.
generateMesh(model)
figure
pdemesh(model);
