heres how a regular "round" goes
The hgs plays a compition, usually a quiz or something, the person who wins in the Head of household or "HOH"
The HOH must pick 2 other people that they would like to nominate for eviction. these two houseguests are on "the block"
Then 6 people play the "veto compition" where if you win you get to have the option to take someone (including yourself) off the block, if that happens the HOH has to nominate someone new
at the end of the week everyone other than the 2 nominees and HOH vote on who they want out, whoever gets the most votes leaves,
then they play a compition for a new HOH, where the previous HOH cannot play rinse and repeat