Try to create one tableau login and try training videos.
If you create a Tableau login, and then check out this link: Author a Viz it's the best place to start!
If you still see a page full of code, try a different browser, or signing up/logging in in-cognito.
Hope this helps.
There is an online training session by Tableau on Getting Started. I’d suggest you to sign up for these sessions.
If facing with technical difficulties, clear cache, try different browsers, or go incognito as others suggested.