The type of wireless headphones I think you had before used an older technology, whereby the device that you're getting the sound from (such as a radio, TV or whatever) doesn't have a transmitter built into it. Instead you plug a transmitter unit into the device's headphone socket, which then sends a signal to your wireless headphones:
https://i.ebayimg.com/images/g/dUYAAOSwjcdhZZrb/s-l640.png
Devices using Bluetooth (such as some mobile phones, tablets, laptops, radios, TVs, etc) already have a little transmitter unit built into them. So you don't need to plug anything into the device's headphone socket. (Indeed, many mobile phones, etc don't even have headphone sockets these days, as they've got Bluetooth transmitters inside them). You simply need to 'pair' some headphones with the device in order to hear the sound.
Both technologies have their advantages and disadvantages. The older one, for example, can send signals over a much greater distance, whereas the newer one (Bluetooth) 'pairs' headphones to devices, so that there's never any interference between the signals.
There's no point in buying Bluetooth headphones if you're using a device that doesn't have a Bluetooth transmitter in it (unless you buy an adapter to equip it with one). Equally, there's no pint in trying to use the older technology with a Bluetooth-enabled device that doesn't have a headphone socket. So you need to choose your headphones carefully!
(If you need specific advice, you'll need to tell us exactly which device it is that you want to hear the sound from).