WW, Lot's of good advice here. You might want to bookmark this thread in your personal page for future reference.

For pictures of Adim7 (Adim) chords, use the Online Guitar Chord Dictionary hosted at the University of Virginia. In the dropdown boxes, choose "A" in the root box and "dim7" in the extension box then click "find chord." You will be presented with fourteen different fingerings for the chord you want. Click on each chord name in turn to see the chord diagram displayed at the bottom of the page. All you have to do is choose the position and voicing that best complements the arrangement you're working on.

I think the simplest way to think about dim7 chords is to remember that they are always a series of four notes each three half-steps above the previous one. A fifth note in the series would be an octave above the first. Since the interval between each adjacent pair of notes is always the same (a minor third) you can name the chord after any one of the notes it contains. In that sense, there are technically only three diminished chords each of which has four possible names. Those twelve names cover all the notes in the chromatic scale and therefore all the possible names.

Good luck,

      - Mark