Yes you can host multiple websites on a single server, or IP.
What webserver are you currently using? Apache?
your virtual host on Apache should look something like these
<VirtualHost *:80>
ServerAdmin
theserveradmin@domain.com
DocumentRoot /path/to/document/root
ServerName
www.yoursite.com
.....
.....
...
</VirtualHost>
Notice that i didn't include the ErrorLog and CustomLog arguments...
You can duplicate that entry to satisfy multiple virtual hosted domains... just change the DocumentRoot under that with your site location, and the ServerName with the sites address... e.g.
www.yoursite.com
btw, if you are using a windows server... you can replace the /path/to/document/root with a windows filepath... e.g. C:/domains/www.yoursite.com/wwwroot/
or C:/www.mysite.com
although I often suggest you put all your sites in one folder e.g. domains... for easy management...
you may also replace the asterisk at the <VirtualHost *:80> with your domain name, although i like it that way for simplicity.
I think If you check on your httpd.conf there is a sample at the bottom of the page.
good luck!