Remember that old joke? "Can you tell me how to get to Carnegie Hall? Sure. Practice...lots of practice". That's sort of the situation here. Mixing isn't something you learn overnight; it's something to spend hours experimenting and trying new things on.
Yeah. Replacing a karaoke mic with something a bit better would help in the future but even now it's worth learning to get the most out of what you already have before you dash out and spend money. The best mic and software in the world still need you to understand what you're doing with them.
A few things to play with:
EQ. Making voice and a backing track sit well together is often a result of careful use of EQ on both tracks. You need to make things sound good together and, at the same time, make sure there's room in the mix for the vocal to stand out of the music. That example you posted has an extremely prominent vocal--almost too prominent to my ears--and the piano is kept warm and subtle compared to the voice which has a real high frequency "edge".
Reverb. Your sample has a fair bit of reverb put onto the voice...again almost too much to my ears. However, if this is the sound you want, you'll need to play with adding reverb to your voice.
Compression: The example you give has a fair bit of dynamics processing (compression) added to the voice to keep even the quieter bits fairly "up" in level and to keep it standing out above the piano.
Mic Techique: Sounds to me like the vocalist was "up close and personal" with the microphone, with a pop shield directly in front of the mic.
...and so on. There's no magic set of settings any of us can tell you to make things sound like your Youtube clip--but just having fun and playing with some of the settings above will gradually let you know what you like and what suits your voice. And, it's fun playing!
Bob