hi friends..
I've need to install a device driver on my RedHat linux version-4 kernel-2.6.
I have the code of this driver in C.
Please tell me to how to install it such that the driver starts itself immediately with the boot up of the system.

You should have a README file with your driver explaining you how to install that driver. Here is the global picture:

1- Install your running kernel source.
2- Unpack the driver source code to some directory.
3- Configure, compile and install your driver.

ie:
Now, if you need more explanations, you should probably give more info like:
- What did you try already that did not work
- What "device driver" are you trying to install
- etc...

Hi,

You need to compile the code first and u must have ".o" object file...
Then you can have lot more option to let the driver attached wih kernel automatically. Either you can manually do it with insmod mydriver.o
or u can put it in rc.local or u can rebuild ur kernel by putting ur .o file at proper place.......

where is the location of rc.local and where is the code placed so that i can add my .o file into it at the proper position..??

rc.local is situated in your /etc directory. Now, inserting a line there to load your driver (insmod /path/to/your/driver.o) might not be a good option, especially if you need this driver during boot time, because the rc.local script is executed after every other script for the specific runlevel has been run.

Unless you are installing some very rare driver coded for the occasion, a decently coded driver should come with some documentation (README and/or INSTALL) describing the configure/build/install procedure to copy the driver in the correct module location for your running kernel (/lib/modules/2.6.x-y.zzzz_DIST/...) and configure your system so that it can be loaded automagically using modprobe (by making some entries in /etc/modules.conf or /etc/modprobe.conf and/or /etc/modprobe.d). Once this is done, modprobe will run insmod for you when it is needed.

As I stated in my first post, this is usually as easy as running "./configure && make && make install".

Now (again... unless you're installing something very rare and unknown...) if you tell us which driver you're trying to install, we might be able to give you more info.