First, make sure that the source is set to TV. (Use the TV button at the top left of the remote to ensure that the TV is being controlled by the remote. The Source button is the one to the right of the Power button on the remote. It's the top button on the side of the TV. ) Next press Menu. (On the remote, it's the button to the upper left of the arrow keys. It's the second button from the top on the TV side panel.) Use the Up/Down arrow keys to navigate to Channel. Press Enter. (Note: the channel buttons at the bottom of the side panel buttons match the Up/Down arrows of the remote. The Source button on the TV is the Enter key.) Press Enter again and use the Up/Down arrow keys to highlight your country. Press Enter. Navigate to Auto Store and press Enter twice. Wait for the TV to go through the channels and test for signal.
You can also add channels manually by using the Manual Store option. If you know the channel number, you would then choose Channel and select C (over-the-air) or S (cable) and then the Right arrow key. Use the arrow keys to highlight the desired channel. Press Enter. Use the arrow keys to select Store and press Enter again. Otherwise choose Search. Use the Up/Down arrows to select a channel. Press Enter, go to Store and press Enter again. Repeat this for each channel.
The manual for the LE26R73BD is available on the support page: https://www.samsung.com/uk/support/model/LE26R73BDX/FID/
. The current link to the manual is https://downloadcenter.samsung.com/content/UM/200603/20060325173246984_BN68-01007A-00Eng-0302.pdf
I hope this helps. If you use a set top box with a non-RF coaxial cable output to the TV, the channel option will not be available.