Fly Fishing Rapidshare Fly Fishing?

Fly fishing? - fly fishing rapidshare

In fly-fishing in a dry stream, which is of great importance that can not fly, but what happens when fly fishing nymphs and wet? I met with conflicting sources of information on this subject, some say that the drag should be avoided, while others say they should consider the possibility, or at least would not hurt. Could someone please confusion that clear for me? It is also the best way to fish before or after casting her?