Howto Detect Webcam Model When Jailbreaking It Says Iphone Not Detected.. Howto Go Into DFU Mode To Jailbreak?

When jailbreaking it says iphone not detected.. howto go into DFU mode to jailbreak? - howto detect webcam model

I went through all the steps to escape, but after dong hold the key for a long time, blah, blah, blah, says iPhone not recognized