[GRASSLIST:3711] Help GRASS5

[Patricia.Jarrin at macosa.com]

Hello that so,
I am making a work in GRASS5 and have had difficulty in using some modulos.
They help to me, my doubts are the following ones: 
1. As they are the steps to obtain a DEM from Curves of Nivel(this file has
an extension dxf). That is the process that I need is from contours, to
happen to raster, soon to interpolate and to obtain the DEM. As they are the
steps that I must follow? 
2. Another doubt is like obtaining a map in format to raster from a file in
format ASCII? 
3.How to make the sobreposition of 4 maps that are in format to raster to
obtain a single data.
4. How handles to GRASS the structure of archives that is maps to raster,
maps vector. 
Thanks for its aid. I wait for its answer soon. Thanks.