Question : on a web application connecting to oracle.  Finding a user session from their computer to oracle

I would like to find a user that signs on to a web application which uses a specific credential to sign on to the oracle database.  somewhere i believe between the web logs, ip address/machine name, sign on user of the machine to a pid that is associated to a sid on oracle.

something like that.  So user John on computer X is signed on with a connection to this SID in oracle.

Answer : on a web application connecting to oracle.  Finding a user session from their computer to oracle

It is most likely that your user sign onto the web application hosted on an application server (or web server). The web server logs onto the database as some generic application user. This makes it difficult to simply query the database for specific wb application user.
A possible way of finding this information is to query for the context user. Both I believe you'll need to create a procedure to capture this information as a logon trigger. There is Fine-Grained Auditing method.

R.