Visvamitrasana is meant to be a peak pose of your practice, so make sure you are fully warmed up before attempting this pose. Pay particular attention to opening the hips, hamstrings and the sides of your waist.
To begin: set up in lizard pose, right knee forward (knee directly over ankle), left knee down, both hands inside your right leg, palms on the floor. Then start to snuggle your right shoulder under your right knee cap. You may only be able to get the upper right arm under the leg instead which should work, but the higher up towards/under the shoulder, the better.
To get into the full pose shown here, plant your back (left) foot down on the ground, setting your back foot down as you would warrior 1.
Start to take the right hand several inches to the right, plant the hand down firmly. Lean back and start to lift the left hand off the ground. Then use your left hand to grab the top of the right foot, fingers wrapping around the outer edge. Start to straighten the right leg as you twist open towards the sky, leaning back. Hold for several breaths and repeat on the second side.
Enjoy the journey!