None of what your friend told you is good to do to marijuana.
It is very small for 2 months old. The height really doesn't mean much, but it only has 3 set of leaves. By 2 months, a plant should be taller, but more importantly, it should have way more branches and budding spots. So, something is quite wrong...let's see if we can figure it out.
First of all, like Rosebud mentioned, your growing medium is very important. The soil you are planted in does not look good. It looks heavy and barky without good drainage properties. I would get some good soil and add whatever you need to it to giver it the proper drainage capabilities and the right amounts of different things. Carefully dig the plants up that you have and set them aside. Now dig a large hole--at least a couple of feet deep and a foot or more around. Now you put your good soil mixture into the hole and plant your plant in that. Make sure that it is a nice sunny location. Marijuana likes a lot of light.
Then you are going to have to get some good nutrients to feed it. Cannabis is a high energy plant and has very specific nutrient needs. We always recommend a nutrient line formulated for cannabis if that is at all possible. Are you in the US and do you have access to good soil and nutrients made for cannabis or can you order online?
Your plant is probably 6 weeks to a month away from even starting to flower. I really don't know what has stunted its growth, but it is the size of a 2 week old plant, not a 2 month plant. So, I really hater to tell you this, but it is like your plant has been in some kind of stasis for those 2 months. Let's see if we can fix that and get those babies growing.
Let us know what your circumstances are and available products and I believe that we can get you on track! The good news is that they do not look to me like they are dying--they just look stuck in the baby plant stage.