The Sierra Sky Ranch Resort is 2 miles (3.2 km) north of Oakhurst, just off Highway 41 on Road 632, which is also known as Sky Ranch Road. Highway 41 is the main (and unless you count hiking trails, the only) southern route into Yosemite.
The road sign is small and easy to miss when you're buzzing past at high speed, but there's a large sign for the resort itself that's easy to spot. Turn right on Road 632 and you'll see the resort on your right almost immediately. If you're driving north on Highway 41, you'll find the road soon after passing the Bass Lake turnoff.
If you're staying at the Sky Ranch, you may want to set aside a few hours to visit the Nelder Grove of Giant Sequoias, roughly 10 miles up the road from the resort. The Lewis Creek trailhead is also nearby.