I wish to install a apk file in beagle board having gingerbread Android. Unable to access files which are in my sdk card.
If you install the files by writing on the SD card it won't work, you have to install them.
The official solution to do so is to call (from the shell)
adb install [-r] yourPackage.apk
(the -r is optional and may be necessary from time to time)
On the beagleboard you usually run a android that is rooted with write-access to system, so installing shouldn't be a problem.
If the adb can't find a device please read the official documentation. You may have to add the usb-vendor id to adb.ini/android.ini and modify udev-rules on linux systems. But all this is documented in the 'android for beagleboard' release you've got.