How do I start dbg?

I have Red Hat 7.2 with whatever version of PHP and MySql came with it, they both work.

I have downloaded dbg-2.11 and compiled, configured and installed everything in /usr/local/bin and /usr/local/src.

phpinfo() looks like it is supposed to.

I have no IDE but various posts imply that I can start dbg anyway - something to do with variable (cookie?) DBGSESSID(?)

So, how do I get the thing started?

Thanks