1. If you have a notebook, format it in the notebook. Download the latest BIOS version, unzip (if necessary) and save it on the USB stick.
2. 2GB are more than enough.
3. With the board outside of the case, on a cardboard or similar non conductive materiel, install the Sempron, apply thermal paste (check on Youtube for how to), install the CPU heatsink, connect the fan to the CPU_Fan header, insert one RAM stick, install the graphics card (check if the card requires additional power), connect the DVD drive (power and SATA cable), keyboard and mouse. With the power supply off, connect the 24-pin and I think that the board has also a 4-pin or a 8-pin 12V connector (I can't find a link to the board).
Check again the connections and power up the board. Enter BIOS, insert the USB stick and look for the BIOS application for flashing it.