Standing Forward Fold aka Uttanasana is a basic posture used in Sun Salutations after you swan dive forward. This pose will help to open your hamstrings and is also an inversion since your head is below your heart.
Start in mountain pose with Big toes together & heels slightly apart. If you have lower back issues feet hips distance apart with the outer edges of the feet being parallel to one another.
Bend your knees enough so you can hinge from your hips and fold over the legs with a long spine
Your torso drapes over the thighs as the crown of the head lengthens down towards the earth
Modification: If you have tight hips or hamstrings separate your feet hips distance apart. Bend your knees deeply so your torso lies between your legs. If you need to heel toe your feet wider than hips then do so to achieve this. You want to feel the complete lengthening of your spine in this pose so do what feels comfortable while keeping your objective to lengthen your spine.
Even distribution of your weight in the feet. Notice if there is the tendency of the weight going back towards your heels. If so draw the shin forward.
Belly is slightly engaged with the bellybutton drawing in and up towards the spine.
Fingers in line with the toes either palms flat on the earth or to your blocks.
Arm variation: Fingers clasp at your low back, palms together as you draw your fists towards the front of your mat or with arms in front of you grab opposite elbows
To get out of the posture release the arms gently down, bring a slight bend to the knees and gently roll back up vertebrae by vertebrae.