How to configure alias, forwarder, virtual domain etc with Qmail?

Take some parameters :

Server : titanic_mail.com
Local domain : disco.com
Remote domain : gmail.com or ureka.com
IP : Remote IP : 209.85.231.83 or 82.98.86.164
A/c : test123@disco.com
A/c : testremote@ureka.com

1. Forwarding e-mail to another host :
a. Go to /var/qmail/control directory.
b. Put entries in /var/qmail/control/rcpthosts like: disco.com
c. Now go to /var/qmail/control/smtproutes and put
disco.com:gmail.com or disco.com :ureka.com //will forward to remote server.
d. Or disco.com : 209.85.231.83 or disco.com : 209.85.231.83:1027 //Port mentioned.

2. Users and alias users :-

Qmail uses a different method of handling users and aliases than do other SMTP servers, such as sendmail. In sendmail, all system aliases are defined in the /etc/aliases file. In Qmail, these aliases are defined in "dot-qmail" files, which are found in the /var/qmail/alias directory for system-wide aliases or in the user's home directory for user-specific aliases.

So, here are the steps :
a. cd /var/qmail/alias
touch .qmail-test123
b. Put the following line in that hidden file.
&testremote@ureka.com or @test@disco.com like this. Just for e-mail forwarding.
c. To forward e-mail to local users, you could inject the e-mail directly into a mailbox file or a maildir directory. Inside .qmail-test, type this line:

/var/qmail/mailnames/disco.com/test/ //for mailbox