you may need to hook up via the composite cable to start with so you can go into settings in the XMB on the PS3. make sure you don't select a resolution greater than your TV can support.
In other words don't select 1080P if your Tv does not support it.
Is your TV HD ready and does it have a HDMI connector.
If it does use the HDMI input as the switching is automatic.
Make sure the Tv also support 60HZ, although if in UK the PS3 is auto set at 50HZ to start with.