To set up a Roku streaming through your TV, you need to enable both video and audio connections. The cords you use will depend upon the age and model of your TV, and what connections you have available. Connect your Roku to the TV using an HDMI cable or composite cables.
Connecting with an HDMI Cable - Look at the ports in the back of your TV. Look for a 6-sided port labeled “HDMI.” It is similar in size to a USB port. It is usually located on the back or side of the TV.
Order an HDMI cable to connect your Roku. Unless you purchased a new model, most Roku players only come with composite video and analog audio cables. However, buying a generic HDMI cable on the Internet or in a box store will ensure a better connection and require fewer cables.  HDMI cables are sold according to their length. They run between $5 and $20. HDMI cables are also preferred because they support 1080p HD video playback.
Charge your Roku in the meantime. Connect your Roku a power source near the TV. Place AAA batteries in your Roku remote.Connect 1 end of your HDMI cable to the Roku device. Connect the other end of the HDMI cable to the HDMI port in the TV.
Turn on your television. Select the HDMI input on the television remote. Either press “Input” on your remote to scroll through the input options, or press the HDMI input button on the remote.
Use your Roku remote to set up the Roku the first time you use it. You will need to type in your wireless password and start using a channel to test your connections. If you don’t have a strong wireless network, you can string an Ethernet cable between your router and the Roku.
Connecting with Composite Cables - Find the audio/visual (A/V) ports on the back of your TV. They should be red, white and yellow. If you only have a green, blue and red port, you will need to acquire a component cable. You can order a component cable on the Internet or in large stores. Component cables support slightly higher HD video playback, at 720p, so you may choose to buy the component cable, if you want to improve your picture. If you buy a component cable, you will need to use the A/V ports to connect the audio. A component cable is a video-only connection.
Charge your Roku in advance. Connect it to an outlet near your TV. Then, put AAA batteries in your Roku remote.Connect the red, white and yellow cables into the corresponding colored ports in the back of your TV. If you are connecting a component video cable, connect the red, blue and green cables now.
Insert the other end of each composite cable into the corresponding A/V port in the back of the Roku. If you are using a component video cable, you should connect the white and yellow composite cable to the white and yellow A/V ports. Then, connect them to the white and yellow ports in your Roku. If you have purchased the HD-XR or XDS Roku and you are using a component cable for video, you can connect a surround sound audio system with an optical cable. This cable may have arrived with your surround sound system. String the cable between the optical cable port in the back.
Turn on your TV. Press “Input” on your TV remote and scroll until you find the Roku. It may be listed as “video,” “input 1,” “input 2” or “A/V” depending upon your television and the number of devices you have connected.
Press the Home button on your Roku remote. Wait for the Roku to search for the wireless network. Enter your password to connect the system and begin using your Roku.