Yeah, a Blu-ray player should work with an old TV, but you won't get any High Definition pictures on there
Anyway. First of all make sure you are plugging your blu-ray player into the Red White and Yellow inputs on the TV. Make sure they are not OUTPUTS. Some TVs have Red White and Yellow phono plugs on the front of the TV which are normally used to connect an old skool video camera. You can try and plug it into these connections.
Alternatively, if your TV does not have these inputs you can get an RCA to scart adapter. Plug your phonos into the adapter, and plug the adapter into a spare SCART socket on the TV.