Assuming you leave your vehicle at the "car park", you'll need to ford the river. Hikers shouldn't have any problems wading across. This road from the river to the trailhead near the wilderness boundary is easy to follow. If there are side tracks, they are very minor ones; stick to the main road. The road will pass through a couple of gated fences.
The road goes through a meadow for about ½ mile before entering the forest. In approximately ½ mile you'll come to a trail junction with the Bear River - Smiths Fork Trail, which runs east-west. A sign points left toward the "Middle Fork Blacks Fork"; the right-hand trail angles back downstream towards "East Fork Bear River"; and of course you'll go straight ahead across the stream to "Dead Horse Lake." About 1 ¾ mile from the Bear River - Smiths Fork Trail junction the road crosses the river again. On the other side of the river there's a meadow where the road finally ends and the hiking trail begins. This is the wilderness boundary and official trailhead where you can sign the trail register. At the south end of the meadow you'll see a building or cabin of some sort.
However, you can avoid wading this stream (and another crossing), by staying on this side next to the river and route finding until meeting up with the trail again. You'll probably meet it somewhere in Buck Pasture (which, by the way, has a footbridge at the upper end for those of you who followed the trail). The walking is flat and easy and you shouldn't find much if any deadfall to impede progress. You may even see a faint trail in some spots, probably made from sheep and deer. There is no danger of getting lost because the drainage is narrow and the trail stays near the stream all the way to Dead Horse Lake.
Back on the trail in Buck Pasture, you'll follow it on the east side of the river for about 5 more miles. It's pleasant walking with grand views on both sides. There is at least one old weathered cabin alongside the trail (one in particular is near it's last breath-- the roof has long since caved in, and a tree has fallen with perfect aim across the middle, breaking the tree in two and almost knocking the cabin over).
You may be wondering where the lake is as you look ahead into the upper basin. Dead Horse Lake is not actually in what appears to be the center of the upper basin, but instead is further to your right, higher than you might think.
About a mile and a quarter before Dead Horse Lake you'll again cross the river, which is much smaller by now, just one of the tributaries. Then you'll start gaining elevation quickly -- as much elevation in the last mile and a half to the lake as you have gained since the trailhead. About ¼ mile from the lake, the trail crosses the stream and ends at a junction with the Highline Trail coming in from your left. Go right, following the Highline Trail uphill to the lake. You may find this last ¼ mile surprisingly taxing (especially if you've carried a heavy pack this far).
The best camping at Dead Horse Lake is on the north side. You can cross the outlet stream on boulders. The camping spots get more and more sparse and rocky the further you walk west along the shore. Be sure to pick camping spots away from the lakeshore, following the "200 feet from water wilderness rule."
Although this basin in general gets fewer visitors compared to some areas of the Uintas, the camping spots at Dead Horse Lake itself are heavily used, since virtually everyone who comes into the upper basin will camp at this lake. For this reason, you may consider camping at EJOD Lake as long as you don't mind the exposure (above treeline).