I don't recommend running vocals into TV/Computer speakers. They are not designed to be used that way. The transient peaks from singing can blow out your speakers. A powered DJ speaker is the way to go. Something like this should work well for you.

https://smile.amazon.com/PRORECK-FREEDOM-15-Rechargeable-Microphones/dp/B072NZK7J9/ref=sr_1_1_sspa?_encoding=UTF8&c=ts&dchild=1&keywords=PA%2BSystems&qid=1594676649&sr=8-1-spons&ts_id=11975001&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEySlhaMjFDUUo2NzBCJmVuY3J5cHRlZElkPUEwNTExMzg5VTExQ0Q3V0FSRVhSJmVuY3J5cHRlZEFkSWQ9QTAzNjIyNDAxUFZIRTBPOElZVlVUJndpZGdldE5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ&th=1