how do you create one hammer there is no display of it

Assuming you're using the current version 0.0.72: Place 2 heated ingots on the anvil. Press "Z" on your keyboard to bring up a radial menu. Click on "Blunts". Press "Z" again to dismiss the menu. Then Hammer the ingots. Happy Smithing!

cheers but it doesnt work with 2 ingots I have to use three with a one hand groo

double check that all ingots are aligned properly, sometimes they do not snap 100% :)