Printing out strings and integers is relatively straightforward.  Here are some
clauses that you can add to your Prolog program:

[user].
prints([]).
prints([H|T]) :- put(H),prints(T).
prints(X) :- write(X).
println(X) :- prints(X),nl.
ctrl-D

The [user]. directive tells Prolog to let you define new clauses.  The prompt
will change to "| ".  This ends when you hit ctrl-D and go back to the usual
Prolog mode wheere the prompt looks like "| ?-".

The prints clause above has been designed to print out strings and integers.
There are also built-in clauses "nl" and "tab(X)".  The former prints a new-line
character, the latter prints out X spaces.  You can print a bunch of things by
using multiple prints clauses, one for each thing to print, including spaces.

The println clause was added as a convenience to print something out and then
print a new-line.  Keep in mind that Prolog is cases-sensitive, so the definitions 
above can be easily messsed up by getting the case wrong.