If your laptop doesn't have an HDMI slot, you can use/buy a HDMI to USB adapter.
You will connect one side of the HDMI cable to the tv and the other to the adapter and the adapter will be in the USB slot.
This is what the HDMI cable looks like:
Look for a slot on your laptop and TV that looks like this:
This is what a HDMI to USB adapter could look like:
(These days HDMI can be used to connect cable boxes as well, when I want to switch from the cable box to my laptop, I just unhook the HDMI cable from the cable box and plug it in to my laptop.)
There are other options, but HDMI is the easiest option as video and audio are transferred to the tv with one cable.
The more "old fashion" way...
If you have an S-video slot or VGA slot or DVI slot and your TV has them as well, you can use one of those cables for the visual connection from your laptop to TV.
Just for a visual reference, the slots:
For the audio you will need to connect your headphone slot to an audio slot on your television, if it's the same as the headphone, you can use this phone cable:
If you have rca slots(usually red and white) on your tv then you can use this cable, black one goes to your laptop and the red and white ones plugged in to your TV audio slots accordingly:
With most TV's these days you will have to change the TV input from TV to either HDMI mode or DVD mode or External mode etc., usually with the source button on the remote control. If all fails, just keep pressing the source button on your remote control(if this applies or any button that will change the TV input)till the image appears on the screen.
The source button usually looks something like this or it might have another name but the same symbol of an arrow pointing in a square or rectangle.:
On other TV's you might have to get in to the menu to change the setting.
Once the HDMI connection is made, in some cases you will have to drag the the image from your computer to the TV with the mouse (basically drag the cursor to the corner of your screen) till the content of the screen appears on the TV as well. I have no idea if that depends on the laptop or on the tv, but try that option if the image doesn't appear on the screen immediately after the HDMI cable has been connected.