At above 1.5 miles, you'll encounter a fork. Going straight will take you on the much longer Middle Fork of the Popo Agie Loop. For this particular hike, you want the left path.
On the hike back toward Sinks Canyon State Park, take a moment to marvel at all the different types of rock in such a close proximity: sandstone, limestone, Dolomite, and granite all in one canyon. No wonder Lander is a climber's mecca!