[1.7.10] Creating a Dimension, and help with liquids.

I need some help How do I go about creating a dimension? I want to be structured kind of like the overworld, but with a custom type of stone and a custom type of grass and dirt. No trees. Oh and a custom type of liquid instead of water. I have already created the grass, dirt, and stone blocks. I need help with the rest (creating a dimension and creating a liquid).