Found this in the information section.
Fishing with a Fly & Bubble
1. Clear sliding bubble
2. One or two-pound leader
3. A swivel
4. A fly
Getting Set Up
1. Slide the bubble onto your main four pound line
2. Tie a swivel on the line to stop the bubble from sliding
3. Run six feet of leader from the swivel to the fly
4. Tie the fly
5. Fill the bubble about half full with water, and...
6. Cast it out there!
Retrieve your fly slowly, try to keep your line tight, and give it a little action like you would a lure. The best time to fish with a fly and bubble is late-afternoon until just before dark. Fishing really heats up late! The lake is the best place to try this technique out, not the creek, although this technique does work in the creek as well.
This is probably the best way to fish Rock Creek Lake from shore, especially late in the day. This is also an extremely effective way to fish the backcountry lakes. Use only one-pound leader in the backcountry, because nearly all the fish that are caught back there are small brook or rainbow trout. Very few trout push or exceed ten inches, let alone a pound in the backcountry. Two-pound leader is appropriate for fishing the lake.