Bottom fishing's generally the way to go for dogs.
The size of lead weight you use will be dictated by the conditions and the casting rate of your rod. Check the rod down near the reel seat for its casting rate. Should say something along the lines of "Rated to cast 3 to 5 oz" Which means the rod is at its best when casting leads of between 3 and 5 ounce in weight.
Practice a few casts with leads in whatever range your rod is rated for, and see what suits you the best / gives you the best distance or results.
In terms of conditions you'll be looking to use heavier leads in rougher conditions in order to keep your rig (terminal tackle) on the bottom. Again you'll find out what suits best when you practice a little.
Be prepared to lose some gear in this area as it can be quite snaggy in places.
Theres a guide to basic rigs etc here which might help to get you started.
viewtopic.php?f=6&t=7724You can also buy pre tied rigs in many tackle shops. Best of luck.