After installation, Brave gives you a small amount of unwithdrawable BAT mainly for you to test out by giving to publishers/websites(and not for withdrawal). If your country is already supported, you can then activate Brave Rewards via the settings, and can earn withdrawable BAT from there by simply viewing ads that are displayed when you're randomly surfing the web.
Note that withdrawing the BAT you've earned through Brave Rewards requires you to send KYC info to Uphold. Just a heads up.
Look like they now stopped giving rewards.
To me , look like browser itself is a wallet as it have some master key (that is asked to be stored at safe place). Actually I use it just for playing one of game, is it can be reason that all my rewards are donatable to publisher. I did not still used it for normal surfing.