BBB Access SPI Interface with C/C++

I have enabled the SPI-Interface, following this guide:
http://hipstercircuits.com/enable-spi-with-device-tree-on-beaglebone-black-copy-paste/#comment-3797

Now my question is: how can I send/receive data via SPI in a C/C++ program?

Never mind this thread, I accidently created two.