I'm new to speedrunning and am trying to set up the "Super Mario Bros livesplit plugin" by wooferzfg1, but don't know how to install and activate it. Any help would be appreciated!

place the file in the 'components' folder of livesplit, then right click your layout, select edit layout, then click the plus, then hover over the 'control' selection and select 'Super Mario Bros. Plugin'. That should do the trick

@CaptainCamerupt this worked, thanks!

Anytime.