Lattice

does anybody know how to use the lattice modifier?

Create the object you want to deform (duh) and a Lattice object. Select your object and give it a Lattice modifier (F9 panels). Enter exactly the name of the Lattice in the Ob: field. Edit the lattice’s control points to deform your object. To get fine control you will probably need to subdivide your object, and increase the U/V resolution of your lattice. Finally, you can create a weighted vertex group in your mesh and specify its name in the Modifier panel, to restrict the lattice’s influence to specific parts of the mesh.

For more details please read this page from the manual.

ok thanks.