When you first start Construct 2 you should see the Start Page, which looks something like this:
This gives you a useful starting point whenever you launch Construct 2. It has some useful links such as Create a new project, Newest tutorials on the website, your recently opened projects, links to our Facebook, Twitter and Google+ pages, and so on.
If you're new, you might want to check out the link to the Beginner's Guide to Construct 2 tutorial. This is a step-by-step guide to help get you going making your first game in Construct 2.
If you like examining existing projects to see how Construct 2 works, you can try opening the Space Blaster or Ghost Shooter demos. These are advanced examples so don't be put off by the math or complexity of them. They're mainly to show off what Construct 2 can do in the hands of an experienced user.
There are many much simpler examples in Construct 2's Examples directory. Click Browse all examples to see them. There are over 40 which go through things like making a simple platformer and physics demos. It's highly recommended to look at all the examples. Commonly asked questions like "How do I set up custom controls?" have examples showing how it's done in the Examples folder.
You can change the Show start page on startup and Close the start page when I click on something settings in the Preferences dialog.