Okay if you wanna search for some PASSIVE stretches, this would be beneficial for Muay Thai and Kickboxing flexibility.
Go into a position of the box splits, and go down as far as you can go without lifting your feet up. lean down and grab your left ankle with both hands, bringing your head to your knee so you feel the stretch. Hold it for 15 seconds, and then do the same on the right leg. Repeat again by putting your body weight in the middle, put your hands on the floor and your head on your hands. Do this all again and in the same position, start reaching out and touching your opposite leg. So for example, keep your legs straight and reach to your left toes with your right hand. Both arms should be lifted up at all times, as if you're making a 'T' shape with your upper body.
Another good stretch is the groin stretch.
There isn't a bigger picture, but that's basically what it is. Just make sure both your hands are to the left of your front foot, and that your back leg does never touch the floor. Point your toes too.
Hope I helped,