Parallel to present perfect with er or har as auxiliary, you'll have to choose between var or havde as auxiliary for past perfect .
1) Han var rejst til Indien, så jeg kunne ikke mødes med ham. (He had gone to India so I didn't have the chance to meet him
2) Han havde rejst meget i Indien, så han kendte landet godt. (He had been travelling a lot in India so he really knew the country well)
In 1) er rejst describes a transition of the subject : From DK to India, whereas har rejst in 2) focuses on the activity, not on the transiting from starting to ending point.
Verbs that take object do not shift the subject between two states. They work on the object, so they usually form perfect with havde.
Jeg havde taget det sidste stykke tyggegummi i pakken. (I havde taken the last piece of chewing gum from the box.)
But for verbs that do not take object you always have to consider transition versus activity.
Choose between var or havde in the drop down menu.