How to reconfigure UPK web.config to use a TNS alias connection on Windows

I have unencrypted the web.config file and can see the <connectionStrings> section with current db server info. I want to replace this with TNS alias and need guidance on syntax.

Also, this is the only Oracle product installed on this server, so there was no ORACLE_HOME variable established and no tnsnames.ora file.

I created a tnsnames.ora file in C:\Program Files\User Productivity Kit\network\admin

Is there a guide to manually establish the required environment variables to facilitate this effort?