Welcome! As @Smiley noted, you can search the forums for answers. You can also read the Help section of the TH website/app. Then there’s the official TH blog, which you can also search. Here’s a blog article just to get you to the right site:
As a new sitter, Christmas is a great time because there seems a lack of sitters. Though you still need to be responsible and responsive! Consider trying to do a local sit or two this month. It’ll be good experience for you.
For example, I know @GardenCat has been looking for a sitter!