This second Samskaram is where the jeevathama gets to know the 12 important powerful points of the body where Lord Narayana resides. And also the name of the Thayyar who lives with him and how does lord look like in those 12 places. These 12 places house the Upavyuvha forms of Lord Narayana. Each of the 12 places are adorned with Tirunnaman Kappu or the Urdhra Pundaras or the Tirunamam.
The white portion is called as Tiruman and represent the Lotus feet of lord and should always be pointing up. The centre line represents the Consort of Lord Narayana. It os adorned with Shree choornam. Some use golden color since the goddess is of golden color (Hiranya varnam Harinieem...). And some use red color.
Sumangalis wear this Shree Choornam in red color and a small Thiruman-like goddess Ghodha Devi Wears. And yellow Shree choornam if they are widows.

Now the Sequence of adorning the holy Urdhra Pundaras are:

1. On Forehead – Keshava. Lord holds Chakra in all four hands and his consort name is Sri

2. Above Belly button – Narayana. Lord holds Shanka in all four hands and his consort name is Amruthodbhava 

3. At the centre of Chest – Madhava. Lord holds Koumodhaka in all four hands and his consort name is Kamala

4. Centre of front Neck – Govinda. Lord holds Saranga in all four hands and his consort is Chandrasodari

5. Right side above belly button – Vishnu. Lord holds ploughshares in all four hands and his consort name is Vishnu Patni

6. Right shoulders in line with the namam on the chest in terms of length and width – Madhusudhana. Lord holds a pounding rod in all four hands and his consort name is Vaishnavi

7. Right side of neck – Trivikrama. Lord holds a sword in all four hands and his consort name is Vararoha

8. Left side above belly button – Vamana. Lord holds Thunder Bolt in all four hands and his consort name is Hari Vallabha

9. Left shoulders in line with the namam on chest in terms of length and width – Sridhara. Lord holds an Axe in all four hands and his consort name is Sharngini

10. Left side of neck – Hrushikesha . Lord holds a crow-bar in all four hands and his consort name is Devadevika

11. On the back on spine above the hip joint – Padmanabha. Lord holds all his weapons in 8 eight hands and his consort name is MahaLakshmi

12. Behind & centre of neck – Damodhara. Lord holds a whip in all four hands and his consort name is Surasundari

These 12 namam also represent 

4 Manthra Samskaram
2 Pundra Samskara
1 Thapa Samskara
5 Yaga Samskaram