As has been said, if you provide the model number (from the back of your monitor) we can probably find a manual for it.
Given that the very first thing you should do with any monitor is to check that it's correctly set up, I'm surprised that you've not discovered what those buttons do yet anyway!
To see if you need to change anything, take a look here:
https://reeddesign.co.uk/testcard.htm
The coloured band should display vibrant colours.
The line below it should have a jet black square on the left and a brilliant white one on the right, with clearly defined steps.
The next line should also have clearly defined steps, going from jet black to brilliant white, and (very importantly) all of the numbers, from 0 to 10, should be clearly visible.
The bottom line should be similar (and, once again, all of the numbers from 0 to 10 should be clearly visible) except that there should be a continuous transition from black to white, with no steps.