The beginning or casual student will no doubt be aware that the grades of the Golden Dawn are attributed to the Sephiroth (barring the probationary grades of Neophyte [0=0] and Portal, which can be seen as an outer court to Malkuth and Tiphareth respectively [it's interesting to note that these are the two Sephiroth with probationary grades before them, hinting once more at their union]). Thus we have Zelator [1=10] attributed to Malkuth, Theoricus [2=9] attributed to Yesod, Practicus [3=8] attributed to Hod, Philosophus [4=7] attributed to Netzach, and Adeptus Minor [5=6] attributed to Tiphareth (the grades above this are not relevant to this post). This is the preliminary and basic understanding of the grades upon the Tree of Life.
However, this is primarily theoretical, and there is a deeper application of grades on a more "realistic" structure, where all four elemental grades are attributed to Malkuth (it being four-fold in structure), with Adeptus Minor technically being in Yesod (the astral realm). Indeed, the sub-grades of Adeptus Minor would actually give a similar structure to Yesod, with Neophyte Adeptus Minor, Zelator Adeptus Minor, and so forth (indeed, all of this within the World of Assiah). This may be surprising or confusing to some people, but the important point to remember is that both applications are correct. There is no "one" way of looking at the Tree, and it is nigh impossible to understand Qabalah in all its depth and intricacies if we don't realise that there are multiple Trees, all overlapping in different and seemingly contradictory ways. This is the penalty we pay as an attempt to understand the Divine, and there's little hope in trying to "dumb" God down to our limited level of understanding.