Are you good at the audios?

[Shrubwise]

So here's my dilemma: Well over a year ago I began using voice chat and invested in some nice headphones, and got rid of my old crappy computer speakers. They were starting to crackle anyways. However my ears are starting to bother me (I think from the long term use of headphones for several hours a day) and I want to go back to using speakers. Not only that but it's hard for all my friends to come over and lol at youtube videos with me when we have to take turns using the headphones.
I picked up some decent speakers a few years ago that were on sale, and put them in storage. I never figured out how to hook them up to my computer. The backs of the speakers look like this, and the wires that came with them look like this (see below)
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My question is this: what do I need to buy to hook them up to the back of my computer? (Speaker out line) If I am not mistaken I think I will need an amplifier of some sort and some cables. I am just not sure which. I won't need anything fancy, I was just hoping to save some cash by picking something up from newegg.com instead of getting screwed by best by. Seriously, the last time I went to buy a USB cord, newegg wanted $4 or $5 for a comparable cord at Best Buy (they wanted $24)

Thanks in advance!