Indeed, stock footage is still the best solution for explosions. You can find some free stuff at www.detonatonfilms.com
and there are numerous sites where you can purchase explosion footage.
A rocket trail would involve a particle emitter with smoke textures, where the particles move very slowly, and are separated form the emitter, so they just kind of hang in the air as they are emitted.
I went ahead and answered this because I was feeling friendly, but you cannot typically expect to receive support for software you don't own.