All of these are pretty much one-liners, I don't know what you would write in a tutorial about these.
Volume and panning are basically the same thing, you just multiply the sample volume with a factor before adding it to the mix (for panning, the factor is different for the left and right mix buffer, e.g. if the sample is panned hard left it would be 100% for the left channel and 0% for the right channel).
Pitch is a bit more complex but still simple... You need the sample's playback frequency (e.g. 22 KHz) and the mixing frequency (e.g. 44 KHz)... Then you compute the relative increment of the sample position, which is sample frequency / mixing frequency (in this example, it would be 0.5). Then, when adding samples to the mix buffer, you advance the sample playback position by this relative increment. Usually this is implemented using fixed point math in trackers, e.g. the relative increment could be a 16.16 fixed point number. As soon as you add interpolation, it gets a bit more complicated, but these concepts remain the same.
