I am new to piano and just downloaded this book, it seems simple enough for a beginner like me but there is a symbol that I don't really understand, a fermata.

Googling I see I am supposed to hold that note sometimes as long as double the original note's value, but as you can see below, that's already a whole note, how can I hold it that long? Won't the note go automatically silent before that?

Basically, I think my question is, how do I get that much sustain?