Connecting a hifi to a computer

Quick question, how do i connect my hifi to my computer? When i bought the hifi, the salesman said i could connect it to a computer, and use the hifi's speakers to play songs on the computer. But i have no idea how. The hifi has 2 sockets for cables, one is labeled L aux, the other is R aux. The manual says it can be used to connect it to a dvd, cdr etc.. but doesnt say anything about a computer.

can you just plug a Y-type cable in there? one that has a 1/8" jack on one side and RCA plugs on the other?
sort of like this

http://rsk.imageg.net/graphics/product_images/pRS1C-2802621_rshalt1_dt.jpg

where as the plug on the far right side goes into your computer where you would plug your speakers into and the other two plugs go into the system. Red is on the right and White is on the left (back of system not picture)

http://www.radioshack.com/product/index.jsp?productId=2273177&cp=2032054&f=Taxonomy%2FRSK%2F2032054&categoryId=2032054&kwCatId=2032054&kw=y+cable&parentPage=search you could find something like this for cheaper though

What he said - you just need the right cable, any electronics store worth their salt should be able to sort you out nicely for about $4.