Can anyone help me to start using blender?
its a type of 3D software used for modeling.
I'm not yet familiar with its functions, and I'm
just a beginner at it...

thanks for the help in advance!

Here's some Blender resources you might find useful:
Blender wiki
Blender Artists Forums
Blender 3D: Tutorial Links List
blenderwars.com
planetannihilation.com
Blended Mind
Blend Age
From start to render
A List Of Tutorial Sites
Blender at pixel2life.com
Blender 3D: Noob to Pro
Digital Video Compositing in Blender
Basic Parenting
blender3dfr
Creating Pixar-looking eyes in Blender
Biorust
Mayang's Free Textures - textures for use in Blender

I tried it once... it takes a ton of system resources though. You've got to have a decent medium-end computer for it to run smoothly, it seems like. I also thought it was too confusing, and hardly worth it.

I would read some of the tutorials above, or stick with GIMP or photoshop.

Try the Noob to Pro tutorial. It will get you started.
If a dummy like me can do it, anyone can.

http://www.blender.org/education-help/tutorials/

http://en.wikibooks.org/wiki/Blender_3D:_Noob_to_Pro

Also check out Blenderartists site for tutorials.

http://blenderartists.org/cms/content/view/17/53/

There's a ton of tutorials out there once you get the basics.

http://www.blender.org/