Use the Generate Mesh icon to generate a mesh.
In the Layers pane, select the model regions that you want meshed.
Click (Mesh tab > Mesh panel > Generate Mesh)
As necessary, select the General, Curves, CAD, NURBS, Tetra[1] or Tetra Advanced tab, depending on the type of mesh you are generating, and make changes to the meshing parameters.
Click Mesh, to launch the Simulation Compute Manager.
In the Simulation Compute Manager, select the solve location, then click Launch. to mesh the model.
Accept the default Global edge length on surface as an initial estimate. If this edge length is too coarse decrease it to 1/3 to 1/2 of the initial value. Alternatively, set the Global edge length on surface to about 2 times the nominal wall thickness for a 3D mesh, and 2 - 5 times the nominal wall thickness for a Dual Domain mesh.
[1] 3D only