Now you'll find the check in button in the upper right corner of your app screen—closer to your thumb! So convenient! 

Tap the new check in button (looks like a map pin) in the upper right corner of your screen to check in to the venue you’re perusing, or to load places nearby. Tap the place you’re at, then add a shout, upload a photo, and share to Facebook/Twitter if you so desire before tapping ‘check in.’

To check in privately, tap the lock icon so that it says “don’t share with my friends.’ Private check-ins won’t count toward mayorships and check-in totals on place pages, but they’ll still show up in your check-in history. You can only make a check-in private before tapping ‘check in.’ You cannot retroactively change a shared check-in into a private check-in, nor vice versa.