Where to find examples in the VTKUserGuide book?

where to find the examples like The following example (Figure 4–5) demonstrates the use
of texture mapping (see VTK/Examples/Rendering/Tcl/TPlane.tcl). I can`t find it

I think the last version of that book was written wnen VTK 5 was in use around 2006. The current VTK Version is 9.0 and TCL is no longer used.

Most of the TCL examples were converted to Python and ended up in vtk-examples, however the names may have changed slightly. If you go to this site, the VTK Book (Visualization Tool Kit textbook) can also be found there as both a series of web pages or as a PDF but not the VTK
User’s Guide.

As a start, have a look here: Texture Mapping.