This along with Day31 and the next two subroutines are hybrid asymmetric vinyasas, each leg is in a different position, here the right in padmasana while the left is in marchi.
I find this half lotus version easier than the backward facing foot from yesterday, the lotus seems to give more stability when lowering my forehead to the mat in pic 3.
Notes for the half lotus are of course the same as in Day 26 but we're required to have a tighter lotus, the foot deeper into the groin to allow the other thigh to come up as we bring the opposite foot to our buttock.
See also Day 17 Vrikmasana for some notes on standing half lotus.
To get into half lotus : Bend the knee bringing it towards the chest, allow the knee to drop out to the side, key here is the natural rotation in the hip joint. Bring the foot close to the opposite thigh, hold your foot in one hand and the knee in the other and GENTLY encourage the roration of the ball and socket hip joint, bring the knee forward parallel with the floor towards the opposite knee and the foot further up the thigh and ideally, eventually, towards the groin.
You don't want to force this action, if you feel strain on your knee it may be better to practice tomorrows subroutine built around mama mudra with the foot against the thigh rather than on top instead. Practicing the maha mudra subroutine will bring half, and eventually, full lotus closer.
As yesterday, for the bind sit tall, stretch out of the pelvis and swing the arm around the knee on the exhalation. Search for the binding hand as if you were trying to put your arm through the sleeve of a tangled jacket.
On the next inhalation stretch tall again up out of the pelvis to straighten and realign after the fumbling for the hand behind your back, then lower your forehead to the mat.
The same goes for the twist to look over your shoulder, sit tall and lift up out of your pelvis to create the space to allow for your body to twist.
Picture 6 is another variation of marchi, a very challenging reverse twist. It's not in Ramaswami's Complete Book of Vinyasa Yoga but if your coming from Ashtanga as I did it's a posture you might miss and slips into the subroutine nicely here.
To get into the reverse twist you need to have the foot on the floor slightly to the left of your left buttock and then tilt the knee inwards. Bandhas need to be engaged, mula to ground, uddiyana to give more space around the midriff. Sit very tall, lift up as high out of the pelvis as possible. Twist as far to left as your able and swing your right arm around your right knee, you'll need to dip your body slightly down to the left to bring the outside of your shoulder as close to the outside of your knee as you can. As you stretch around to bind your shoulder brings your knee over, half way around you come out of the dip and stretch up out of your pelvis again while twisting to look over your shoulder. There is a tendency to drop the left shoulder, you'll need to keep it high to be able to reach the left hand behind your back.
The reverse twist is challenging and can take sometime to master but many of the principles are the same as the upcoming purna matsyendrasana, another posture that we gradually work towards.