i'm a begginer in dioramas and i want to know how to make the ground

There are a number of ways to create the ground work for your dios. I'm assuming you want dirt or grass, and not a street........
The method I use is out of Shep Paine's "How to Build Dioramas". If that book is available to you, I recommend it. I mix up some Celluclay, which is just an instant papier mache and I put this on my base. I sculpt small rises in the ground, making it more natural. Before it's dry, I will stick various sizes of pebbles (usually you don't want round ones) into it and sprinkle with some sand for texture. That works great for desert scenes. If you want grass, you need to find some model train builders' static grass. You just spray some glue onto the groundwork and then sprinkle the grass over top.
I don't mean to toot my own horn here, but I wrote an article on the making of a simple diorama meant to help beginners. You might find it helpful: Article

Nic

thanks you but here the is no railroad shop and i can;t find grass. what else can i use?

oh and somethin more. what do pebbles means? andd must i paint the ground?

Pebbles, like little rocks. Find different sizes. I forgot to mention before you can use normal dirt, too, for a different texture.
For grass, find something that is thin fibres. Maybe you could cut the bristles of a paint brush, but you'd need a lot of them. I know Verlinden makes static grass. You could order it.
Sorry I couldn't be of more help,

Nic

I try to use as much natural supplies as possible.
First you can't beat the way it looks
Second its cheap.

I use sand, fine washed, dried plant roots.
Clean Kitty Litter is also very good for ground cover and damage.
Old paint brush bristles for long grass.

Just use your imagination and look around.

so i can make grass by plant roots?