Just got my SIP trunk, whats next?

I installed Asterisk yesterday, set just two extensions, and I can use softphones to call from one another inside my LAN.
Today I got a SIP Trunk from Nextiva in US, they gave me some basic parameters to configure my Asterixk (Authentication Name and Authentication Key).

Im very new to this, what I need to do to test outgoing or incoming calls to regular phones using my softphones?
(looks like I have to set some dialing rules and a plan or something, but first time I saw the Asterisk software was yesterday, so Im giving my first steps)

Little help would be awesome.
Thanks guys.

Bump, little help please.

Please read the posting guidelines, about bumping, then read asteriskdocs.org/

Welcome to Asterisk!

Here are some helpful resources for those who are new and simply need general advice for getting started:

Asterisk 123 Videos:
youtube.com/playlist?list=P … ghW4tpwpRg

Asterisk the Definitive Guide:

Official Asterisk Training Classes: