I need help adding UTM tagging in marketo LP's. We have recently added GTM code on our marketo template, I now need to UTM tag all the landing page URL's, so that I can see it in my GA as one session. I use google URL builder to do that once I get the UTM URLwhere do I put the UTM coded URL in Marketo? Is it in the meta title or custom Head HTML?
You don't put the UTM codes anywhere on the LP itself, you put them on links to the LP (either from emails, ads, or other pages).
In other words in the href of any <a> tag.
If my LP URL is pages.example.com.au/webinar-2016, I UTM tag it to pages.example.com.au/webinar-2016?utm_source=test&utm_medium=landingpage then advertise it as a link on my website example.com.au (CMS based) i need to go in the CMS and enter it as <a href="pages.example.com.au/webinar-2016?utm_source=test&utm_medium=landingpage">Webinar</a> and no further implementation is required in marketo, is that right?
Right. Marketo LPs don't have any innate awareness of the UTM parameters you've added -- they're just "foreign" query params that are ignored when rendering the page. But if they're present, GA/GTM or other analytics packages can make use of them.
Marketo forms can be made aware of UTM parameters by creating hidden fields that AutoFill from query params. In this way you're able to link params to known leads in the Marketo database, in addition to having them on the anonymous web tracking side. But without this special config, everything works fine. They're just ignored.