Looking to allow access over the web

Just discovered this great software, and we are looking to test the capabilities in a sandboxed environment. How would I configure access for our small business, so that we may use the messenger remotely/outside of our lan?

We are currently only testing with a small group, and such, are using the default database that openfire offers.

Thanks!

Edit: We also, donot use a DNS, as the office is really only used for collaboration occastionally, and we just never set one up. Everything is routed through a static business line address. *added this note in case, its asked about the DNS.