Problems to use symbolic first time

[Leo Baumann]

Hello,

typing the command "syms x" I get following error:

>> syms x
Der Befehl "python" ist entweder falsch geschrieben oder
konnte nicht gefunden werden.
OctSymPy v2.6.0: this is free software without warranty, see source.
Initializing communication with SymPy using a popen2() pipe.
error: Cannot run the Python executable "python"
    Python and SymPy are needed for most Symbolic features.
    Is Python installed?  Is your "path" configured correctly?
error: called from
    assert_have_python_and_sympy at line 24 column 5
    python_ipc_popen2 at line 78 column 5
    python_ipc_driver at line 59 column 13
    python_cmd at line 164 column 9
    valid_sym_assumptions at line 38 column 10
    assumptions at line 82 column 7
    syms at line 97 column 13

What have I to do to get it work?

thanks - Leo