The voting power calculations are a bit complex, but essentially you have a buffer of roughly 5 days. So if you vote a lot each vote slowly gets worth a small bit less. And over time that recovers.
Basically, you can vote 20 times but each vote is only half the worth of when you only vote 10 times.
And Minnowbooster uses your voting power when your buffer is overflowing. At the top of this post is a primer that explains in detail how to sell your vote :)
I see. I will soon try this I believe. Thank you very much for your patience and effort/s with me.