[beagleboard] Run Angstrom tar.gz image on C4

I used online Angstrom builder. It created my console tar.gz image. I
downloaded that file. The contents looks like root file system.
Could you provide steps how to put that image on SD card and run it? I'm
noob but I suppose I need bootloaders files and kernel image. In online
builder I had among other things:
  * angstrom-uboot-scripts
  * u-boot
  * u-boot-mkimage
  * x-load

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