If your using tent guy line cord for your tarp (you don't need to use paracord) the simple method is using
http://www.amazon.co.uk/dp/B005XCND...d=14992086531842833841&hvpone=&hvptwo=&hvqmt=
http://www.amazon.co.uk/dp/B005XCND...d=14992086531842833841&hvpone=&hvptwo=&hvqmt=