Wherever, whenever and however you want to is the short and somewhat glib answer. To be more helpful:
Singing for your own pleasure can happen almost anywhere. The traditional (and for some people), still the main place to sing is in the bath or shower. There is even a song about vocalising one's ablutions: Michael Flanders and Donald Swann's 'In the Bath'.
Singing for other people's benefit and pleasure usually happens in concert venues or places of worship.
Recording your own voice is relatively easy and you might be hoping to make your singing available to others on CD, mp3, video or online.
Whatever your preference or aspiration, few people who sing would claim to have a voice that cannot be improved. Professional singers maintain close relationships with their teachers or coaches, relying their expert eye and ear to notice, identify and help to remedy any slight loss of quality or control, any mannerism or bad habit, before it becomes a problem that will be noticed by audiences.
If you live in the south-west of the UK and would like to sing in one of the many choirs in that area, please look at the web-sites listed on the Links page.
Singing for your own pleasure can happen almost anywhere. The traditional (and for some people), still the main place to sing is in the bath or shower. There is even a song about vocalising one's ablutions: Michael Flanders and Donald Swann's 'In the Bath'. 
Singing for other people's benefit and pleasure usually happens in concert venues or places of worship.
Recording your own voice is relatively easy and you might be hoping to make your singing available to others on CD, mp3, video or online.