I have a zenith flatscreen tv...looks like a monitor..it has a port to connect to the computer..which cable do

i need to buy? I bought an svga monitor cable from best buy..that's what they told me to use. I connected them..and nothing is happening..i went to video..and component on the monitior and nothing..so i am guessing that either i am not connected right.have the wrong cable..or just plain dumb..