I am relatively new to blender. I am making a model of a crate that is going to contain some fruits. I don't want the fruits to pass through the crates nor the fruits to pass through/overlap each other. Is there a way to do so?
in your case I would try to deal with that by using physics. On the right side of your blender window is the menue, select physics in the bar.
Click on your crater that will later contain the fruits and add Rigid Body. You will have to make it a Passiv Object, that means that it won't fall into the abyss (like when it is active), and that active objects don't pass through it.
As soon as you have created your fruits, position them for example over your crater. Under physics add again Rigid Body, but this time make them Active (which should be automatically be selected).
Now when you play your animation the fruits should fall into the crater and maybe bounce a little bit, neither will they go through the Passive object and nor through the other fruits that are Active Rigid Bodys as well.
I hope that answers your question. If you can't find those options in blender, I'll post some pictures to describe it better.