If you're betting via an online agency, it's pretty straight forward.
Just add 2 or more events to your betslip and at the bottom there should be an option to combine all bets or "create multi" and it will combine all the bets you've selected.
Although just be mindful that you can't multi 2 bets if they're from the same event. i.e. You can't multi Lakers to win and 1st Quarter winner Lakers in the same match.
Hope that makes sense