Upgrade Recommendations To Accommodate Streaming

Hey guys! I want to stream Hearthstone and somehow my computer is so fucking bad it can't handle even that. I know nothing about computers but I'm looking for the cheapest way to be able to stream. I can play the game no problem on my current PC. Not sure if it's best to do a new build or upgrade what I've got. Current specs:

HP ProDesk

CPU: Intel i5-4570 3.2GHz

GPU: Intel HD Graphics 4600

RAM: 8GB

The computer hard drive has 536mb available and I have a 1TB external hard drive as well.

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I'm not sure what other relevant info would be needed that's what I can find in settings. If you can help me out I would seriously appreciate it.