Shiva Purana
कल्पयेदासनं पश्चादाधारादि यथाक्रमम् ॥ आधारशक्तिं कल्याणीं श्यामां ध्यायेदधो भुवि ॥ २२ ॥
Afterwards one should arrange the seat, the base and the others in order. One should meditate on the auspicious darkness of the base energy on the ground below.
english translation
kalpayedAsanaM pazcAdAdhArAdi yathAkramam ॥ AdhArazaktiM kalyANIM zyAmAM dhyAyedadho bhuvi ॥ 22 ॥
hk transliteration by Sanscript