Updating CName Records

Hi guys, i am slightly stuck in the installation process. For some reason my domain provider has suggested i add the cname files via my hosting account(where my main domainis hosted) while tryinna do this i am finding it difficult getting valuses to insert as cname… Please see the image below, i would be glad to get help on this here.
What value am i to insert in the Cname section below?

BTW my discourse installation at discourse.example.com is coming up but seems to be broken. i think this may be the cause and fix. Would appreciate any help getting this done.
Thanks Guys

Thanks done this, Great Documentation and support you put together. Just have a slight issue with the updating cname as there is no record to point to. Could you kindly checkout this thread and help out? Thanks Updating CName Records