I agree with the importance of fiber AND with the importance of squatting. When I have to poo, I squat down in my shower and poop in a pie tin...and when I'm done I simply dump the contents in the toilet and rinse the pie tin off under the tub faucet and store it away until the next time. (Is this too much information?? lol) Honestly, squatting for evacuation is the best, and it helps the poop to come out more fully formed.
But fiber is extremely important: Buy some "Double Fiber" bread by Oroweat and eat several slices a day, also avocados, lentils and beans (well cooked), and ripe pears are an EXCELLENT fiber source, and oat bran as well. These suggestions are just to get you started, they all have a lot of fiber content. If I were you I'd do research on the best fiber foods, make a shopping list that includes these foods, and then proceed to completely change your eating habits. Over the course of about 5-10 days, a high fiber diet, combined with squatting for BMs, will start to really change your whole pooping experience for the better.
I have been struggling with constipation & hard pebble-poo for a very long time. I have done many enemas in my life and tried various different things, but it's only now that I'm getting really serious and taking control of my bowels, so to speak. And so far so good!