I do not have a fish locator so what should I do to find areas to fish offshore, I have found some help with Navionics Web App but is there any thing else I should do?  

Navionics is a good tool to use. It will help you locate ledges, humps, etc.  Without any kind of sonar you will not know what is on the bottom( limbs, stumps, rocks, etc.)  You may can ask any friends that fish the lake or river what kinda of cover or structure is located in certain areas. 

http://www.bassresource.com/bass-fishing-forums/topic/138595-ledges-on-topo-maps/

Carolina Rig

Bing maps birds eye view and as said a C-Rig.

 

But you would really fair well by having a very simple and cheap depth finder.