Advice on how to revamp pine dining table

[sydenhamhiller]

Hi, I am sure this seems like a ridiculous question but DH and I clueless about this sort of thing, so I thought I would seek the wisdom of MN. We bought a 2nd hand dining table about 3 years ago. DH sanded it with an electrical sander...and now after 2 years, 3 kids, paint, glue guns and various other stuff, it is quite marked.
I've browsed the internet, but I am not sure what to do: electric sander, then sand paper, then some kind of sealant? No electric sander (mouse?), just various types of sand paper, then wax? (People seem to have different opinions about waxing.)

All/any advice gratefully received.