It's very easy to cast your smartphone display to your TV
via WiFi or by using cables.

Most of the main and popular Smart TV manufacturers like
LG, Samsung, Sony and Panasonic provide features for
users to connect tablets and smartphones to their TV via
Wi-Fi or cables .

For instance, Samsung and Sony’s new Smart TV models
have a ‘screen mirroring’ feature that lets you display
whatever is on your phone screen. You can transfer videos, photos, and also stream YouTube to your Smart TV with your tablet and smartphone. While the YouTube application for Android can be connected easily to a television through the streaming icon, displaying multimedia like videos and photos takes a little more effort.


You can use iMediaShare to connect to your Smart TV. It
allows you to transfer music, photos, and videos from your Android Smartphone . With the iMediaShare app, you can select
any file type and also play videos serially on your Smart
TV.

You can also use HDMI cables to connect your phone to
your Smart TV.The High Definition Multimedia Interface (HDMI) cable is the ultimate interface standard. Most Flat-screen TV's
come with a HDMI port. HDMI can easily accommodate
HD videos and audio simultaneously, letting you connect your smartphone without bothering about watching a HD movie but making it incredible with your smartphone’s tiny speakers.


HDMI plugs come in 3 sizes. Regular HDMI plugs (Type A)
which have full-size ports which you will find on TVs, game
consoles, and laptops. The ports you'll find on smartphones and tablets are either mini HDMI, middle (Type C) or Micro HDMI, right (Type D).


Of these , the Type D, or Micro HDMI is the smallest. No
Matter the kind of smartphone you have, connecting it to a
HDMI socket won't cost you much .


You can also use the SlimPort/MHL.Just like HDMI, MHL and SlimPort support both audio and video. However, both need breakout boxes, a small dongle on your device and a Smart TV that can convert the signal from your smartphone to one that is compatible with HDMI.

MHL has undergone several versions, it's currently on the third version that improves the resolution to 4K. This also applies to SlimPort. If your Smart TV doesn’t support the MHL or you have a SlimPort handset, you will need to buy an adapter. With three versions of MHL and SlimPort, you have to make sure your device meet the specifications before purchasing an adaptor.
I suggest you use the HDMI since it's the easiest one to set up.

Source - http://www.naijatechguy.com/2016/10/how-to-connect-your-smartphone-to-your.html