I suggest looking at
JaredC01's Tutorial... everything A/V is in there, including this. Good chance that any questions you have will be answered there.
And 'cause I'm a nice guy, I'll throw in a list of components for you, even though they're already listed on the diagram... you'll need a vga connector, something to connect to the back of the xbox (such as an opened up xbox A/V cable), one 680K ohm resistor, 2 - 0.1 microFarad capacitors, and an LM1881 or LM1881N chip. If you don't know what any of this means, find an introductory book on electronics and READ IT... this is simple stuff(no offense) that you can learn about in a couple hours of reading.
I'm sorry if I'm having trouble understanding why you're confused... the tutorial you refer to lists the components needed (same ones I just listed)
The lines on the diagram are WIRES... long lines of metal with plastic insulation around them. unless two lines meet in a T on the diagram, those two wires should not be connected.