I downloaded the 64bit Windows installed for "Tor Browser" from this url

https://www.torproject.org/download/download-easy.html.en

It installed and worked as expected and can display normal and .onion sites.

The first default page it displays is about:tor

Under "you can help" there is a link called "Run a Tor Relay Node »" to

https://www.torproject.org/docs/tor-doc-relay.html.en

which says

Alas, since Vidalia (a graphical interface for Tor) is no longer included in Tor Browser, there are currently no easy relay packages for Windows and OS X users.

followed by "Configure Tor by editing the torrc file"

I edited my "....\Tor Browser\Browser\TorBrowser\Data\Tor\torrc" file as directed and added the port forward to my firewall.

Unfortunately the Tor Browser failed to start after that and entered a "failed to start, need to restart" loop.

I enabled debug logging but nothing was added to the log during these events. I reverted the edits and verified the logging system actually worked. I trawled the tor site, google and this site for further explicit information with no luck.

I am now assuming that the "Tor Browser" is 100% client and cannot relay traffic for any other users of the network.

Am I correct ? and if not, how do I active the relay functionality. Thanks.

Clarification

I understand and followed the instructions on the Tor site. What I don't know is if they failed because they were never intended to work on the Tor Browser or for some other reason.