I want to change the white background my eps log to the transparent one. I have download GIMP and INKSCAPE but i don't know what tool should I use.
The eps file is here and i donwload the png version to see what the figure looks like.
Usual technique in Gimp:
Result, transplanted on a contrasting red background to show the absence of halo or jagged edges:
The EPS you linked to is simply a low resolution bitmap image contained inside an EPS container. It contains no vectors. So you can't edit it with Inkscape or other vector software. You could of course recreate it in Inkscape if you really want to.
In GIMP try Colors > Color to Alpha, and click OK.
Export as PNG or TIFF if you want to maintain transparency.