Question

I have started learning TCL scripting language. I use ActivateState Tcl Devkit 5.3.0.
When I create new simulator it gives mistake like this:

invalid command name "new"
    while executing
"new Simulator"
    invoked from within
"set ns [new Simulator]"

Answer 1

There is no command newin Tcl.

So it is provided by some package or by some modified shell.

Assuming you use ns2 or something like that, you need to use the appropriate shell or load the package via package require into a normal tclsh shell.