Not sure how to create a new tab from here - do you have to navigate to an existing song first?
Also there is a spelling mistake on this page, "If you want to contribute TheoryTabs, check out the TheroyTab Contributor Guide".
There are two ways to launch a new TheoryTab Draft
1) (my preferred way) Hover over the account menu and click “My TheoryTab Drafts”, then click “New TheoryTab Draft”, as shown below
2) From any TheoryTab page, hover over the “More” link in the header, and click “Add a New TheoryTab”
Hope that helps.
Also, I fixed the spelling errors. Thank you for point them out.