Basically you need to open Qsynth, load some soundfont ("Setup...", "Soundfonts") and that should be it. Then in Pd, go to "Edit", "Preferences" and where it is written "startup flags" add the following:
-alsamidi. Restart Pd and open Qsynth. Now in Qjackctl, go to "Connect" then "ALSA". You should see Pure Data as an output port in the left pane and Qsynth (it may be written FLUID synth) as an input port in the right pane. Click on both, then click connect, and that should be it! Now all MIDI information generated from Pd will be sent to Qsynth. Also note that you may need to manually connect Qsynth and Pd every time you need to use MIDI.
As for your algorithm above, what exactly are you trying to accomplish? Basically, the first [osc~ 440] is oscillating between -1 and 1 at 440 times per second. When you connect it to [*~ 100], it is now oscillating between -100 and 100 with the same frequency. Then you are using this numbers to change the frequency of another [osc~], so it is trying to go from -100Hz to 100Hz, which should generate some crazy glissandos. But then you still connect it to a [*~ 30], which will generate some really really really really loud sound and clipping and distortion. When using simple oscillators, I normally multiply them by [*~ 0.3] or [*~ 0.4] to make sure the sound is not that loud, because the default range of -1 to 1 is way too loud.
I hope this helps, let me know if the explanation above was understandable.