What type of rifle did you get? What ignition does it use and what is the twist rate if you know it?
All these questions can lead to answers, heh or sometimes more questions.
To answer about powder check out Southern Muzzleloading: The Flash and Bang: Powders and Primers
for a run down of most of the commonly found powders on the market. Blackpowder requires careful storage and handling. More so than its substitutes. However some people swear by the real stuff.