Configuring Asterisk with account

Can anybody help me in configuring asterisk sip.conf, iax.conf, extensions.conf and modules.conf files to work with SIP account. I have tried so many things but its not working for me. To make calls I am using ZoIPer softphone.
Thanks in advance.

Option 1: show us what you tried and detailed logging so we can see what is going wrong;
Option 2: request paid support on the Biz & Jobs forum.