dell optiplex come with with a pcie and pci slots not sure what kind of tv connction you want.
you included the fact that you purchased a shoebox of y adapters and splitters so i asume that you want dual display, a pc monitor and a tv. if that is the case i would check outhttp://www.newegg.com/Product/Product.aspx?Item=N82E16814131451
they do dual display and have vga -dvi and hdmi
for a coax connection get a tv card
these range from 20 $ to a few hundred depending on your needs