The Dead Good DADGAD book is an excellent starting point for studies in this great tuning! The assumption has been made by the author that someone using the book has a good knowledge of the guitar already. As DADGAD is a different tuning from the normal EADGBE,  all the chord shapes will be different, but techniques used on guitar in standard tuning can be carried across to D modal tuning to very good effect. This book is a useful resource and reference work which can be consulted as you develop familiarity with the tuning.