In general, AMD FX 4300 BE (Black Edition) is applied for all the AM3+ motherboard, because it has a de-facto TDP, 95W, and almost all motherboard designed for AM3+ would meet this requirement. I suggest you update the BIOS or firmware to the latest and clear CMOS before installing your new processor. If you have done so, this problem still lies there, I guess there might be something wrong with your processor. In this situation, you can contact with your vendor to make replacement. Anyway, Ich wuensche Ihnen viel Glueck!
Have you built a computer before? Which motherboard are you using? The FX4300 should work in any motherboard with an AM3+ socket.
The steps should be pretty straightforward:
Mount the motherboard in the case
Insert the CPU
Mount the CPU cooler cooler
Insert the RAM
Connect the case front panel wires to the motherboard
Connect the power supply to the motherboard
Insert video card (if needed)
You don't need a hard drive or mouse yet because for now you just want to see if everything is working.
At this point you can hit the power button to see if the computer starts.
You should hear the fans turning.
After a minute or so you should see a message that says something like "no boot drive". That is OK since you haven't mounted a hard drive yet.
That is OK. Now just restart the computer and press the required key to get into BIOS (some use the Delete key).
Can you get this far? If so you are 90% there.