how do you play the music whilst recordin on to it ?

hello just wondering if anyone knows why when i want to sing onto a track it seems tht the track doesnt play whilst im singin
also wen im recording the output meter doesnt do anythin exept the input does

The output meter is not doing anything because Audacity is not playing the other track(s).
To play other tracks while recording a new one requires that option to be selected in Preferences (Edit menu > Preferences > Audio I/O > “Overdub: Play other tracks while recording new one”)