Kara Nyasa

[part of the mūlamantra] anguṣṭābhyāṃ namaḥ
run the tips of your index fingers along your thumbs, from base to tip

[part of the mūlamantra] tarjanībhyāṃ namaḥ
run both thumbs on both the index fingers, from base to tip

[part of the mūlamantra] madhyamābhyāṃ namaḥ
run both thumbs on the middle fingers, from base to tip

[part of the mūlamantra] anāmikābhyāṃ namaḥ
run both thumbs on the ring fingers, from base to tip

[part of the mūlamantra] kaniṣṭhikābhyāṃ namaḥ
run both thumbs on the little fingers, from base to tip

[part of the mūlamantra] karatala karapṛṣṭhābhyāṁ namaḥ
run the opened palm of the right hand on the front and back of the left palm, repeat the same for the other palm

Ṣaḍaṅga Nyāsa

In Paraśurāma Kalpa Sūtra (PKS 3.19) we find directions on the performance of Ṣaḍaṅga Nyāsa. The scripture tells us that the establishment in the six limbs, is done by placing the number of fingers with the counts three, two, one, ten, three, two, respectively at the six points in the body. The commentator Rameshvara notes that according to Dakṣiṇāmūrti Samhita the meaning is - the heart is done with the middle three fingers, the head with two fingers (middle and the ring fingers), the śikha with one finger (thumb), kavaca with 10 fingers, the eyes with three middle fingers and the astra with two fingers (index and middle fingers).

Image source: Gudrun Bühnemann, "The worship of Mahāganapati according to the Nityotsava"

[part of the mūlamantra] hṛdayāya namaḥ
[touch your heart with the middle three fingers]

[part of the mūlamantra] śirase svāhā
[touch the top of the head with the middle and ring fingers]

[part of the mūlamantra] śikhāyai vaṣaṭ
[touch the back of the head with the thumb]

[part of the mūlamantra] kavacāya huṃ
[cross both the hands and touch the shoulders, with all ten fingers]

[part of the mūlamantra] netratrayāya vauṣaṭ
[touch your "three" eyes with middle three fingers]

[part of the mūlamantra] astrāya phaṭ
[go around the head clockwise and strike the left hand with the index and middle fingers of your right hand.]