
Modify yaws.conf as:
%% add path to yapp and yapp example - modify to your own installation directory
ebin_dir = $(prefix)/lib/yapp/ebin
ebin_dir = $(prefix)/lib/yapp/examples/yapp_ex_1/ebin

%% add yapp runmod
runmod = yapp

%% add to first <server ...>
         arg_rewrite_mod = yapp
         <opaque>
             yapp_server_id = external
         </opaque>

%% add to second <server ..>, that is to <server localhost>
%% note you will only be able to access the yapp admin interface from http://localhost[:port]/yapp/
         arg_rewrite_mod = yapp
         <opaque>
             yapp_server_id = internal
             bootstrap_yapps = yapp
         </opaque>

