Practical Guide on How to Set Gas Fees?

hello,

im sure this is not an uncommon question.

but the tutorials i found online never really used the data some website offer for calculation but rather just input a number (therefore i never felt i could replicate it).

so my case is simple: i want to send ETH and USDC to an exchange (no hurry).

i want to use the live data we get from sites like https://ethgasstation.info/ or https://txstreet.com/v/eth-btc

since im not in a rush i would like pretty low fee even if it takes 12 hours or so.

how can i use the numbers on those websites to input the 3 values in metamask (gaslimit, max priority fee, max fee).

like is there a simple calculation that i can follow (base on the numbers from the above websites)?

hope someone can help or link me to a guide that uses actual numbers for calculation!