On your TV start with the most accurate picture mode (usually warm2 color temperature in movie, or expert, or 'creator' mode.), and deactivate most image post processing (this can be done later as well).
Also, in SDR rec709 you can calibrate powerline 2.2. or 2.4 gamma, or BT1886 gamma. When learning, usually start with 2.2 (TV has to be set to 2.2 gamma as well (usually)). Thats sRGB web standard.
(Bright room, web content.)
SDR brightness target for white is 80-120 nits (usually 100 (80 mostly for web content (sRGB standard), or if 100 is too bright for you subjectively), 120 nits in a very bright room. HCFR will suggest 120 nits as a target by default - but the orient itself alongside your measured brightness (luminance) level of your actual white point (100 IRE). What you set it to (usually using the contrast and LCD backlight settings) is up to you. If in doubt choose 100 (nits).
Powerline 2.4 would be "the movie standard", except for when it wasn't and 2.2 was (postprocessing studios agreed on that midway through the Bluray era.
) (Dark room viewing).
BT.1886 is supposed to be 'near 2.4, but with some black compensation, if your TVs black level is not great'. It "emulates CRT" behavior. That said, on devices with a very bright black level its a flawed standard, as it will do WAY too much black compensation and overbrighten an image. So start with 2.2 and 2.4, and then maybe also look into doing a BT1886 calibration.
(You manipulate gamma using 20 point greyscale controls on your TV as well (using the luminance part of the control) - if needed (f.e. if your TV doesnt have a BT1886 gamma preset).
If your black level is 'abolute black' (indefinite contrast), BT1886 == powerline 2.4 - so in that case there is no difference between the two.
And thats all you should know to get going. .)