Asterisk as a hosted PBX for voip selling purposes

Good day ,
I am still very new to voip and this forum
I do have a very good knowledge of networking

I own a small Wisp company and want to start selling voip as well to my current and new clients
I have a supplier that can supply me a Trunk but I need to know more about Asterisk and its abilities because we all love open-source.

can someone point me to links of possible examples or tutorials to setup such a system using Asterisk ?
I need to add multiple clients and also small medium businesses.

Any information will be greatly appreciated

Best Regards
Ferdi

FIrst of all you should start reading https://wiki.asterisk.org/wiki/display/AST/Home and http://www.asteriskdocs.org/ (which is based on old version of Asterisk but I insists to go through it to understand structure and concepts)
–Satish Barot