Worm advice

I'm new to gardening and have no knowledge about this black art This year is the first year that I've started working in my garden. By the looks of it the garden has never been worked and has basically been neglected. The soil is a pretty dense clay and i would like to find a way to improve it. I've started turning the soil and mixing in leaves to help break it down a bit.
I was thinking of introducing worms to help improve the soil but would like some suggestions as to what kind i should get and a rough estimate as to the weight of worms to the square meter! I live in Italy and the climate is in the late 30 Deg in the summer and -10 Deg in the winter with a lot of ground frost.
Thanks for any help

 

Hi Armandii,
from time to time i will find the odd earth worm. I planted over 120 hedges earlier this year and they are growing, some faster than others. I mixed a product into the clay which helped provide nutrients to the hedges.
I was actually thinking of composting worms to help break down the clay. I read somewhere that they would help speed up the process.

 

Thanks for the info. I'll do that

 

There's a few threads Here you might find useful