seeing anything on screen

[mair]

Help! We have done everything to get started but the tv screen on hdmi does not detect any input. Can you please help? Many thanks. John

[DeeJay]

Maybe 'trying everything' includes this http://elinux.org/R-Pi_Troubleshooting# ... put_at_all troubleshooting advice, but if not it's worth a look.

In addition -

Do you know that the cable you are using is OK? Do you know that the HDMI input you are using on the TV is OK? [To check both, can you connect up some other signal source like a dvd-player or freeview box using the same cable and port?]

[FTrevorGowen]

I was "pipped at the post" by DeeJay for my main point but would also add:
1) Have you tried with the T.V. switched on and in HDMI mode before plugging in/booting the Pi?
2) Have you tried just using the (albeit low res.) A/V mode via an "RCA yellow plug" cable to the T.V. A/V input (as used by old VCR's, DVD player's, Playstation etc.). If your T.V. only has SCART A/V connectors it's adapters are available (often supplied with camcorders, Playstation, XBox? etc.)
Trev.