Well you can't. Seems Fox news bought up all the tickets so they could distribute them to who they wanted, keeping out any dissidents in the crowd that they could.
You most surely can attend the protests outside. Assuming you're in Washington, of course. Directions and more below the fold.
Please Rec this, first and foremost, so anyone in the area can get directions easily. The protests start at 5:30p, but the hullaballoo will be starting earlier most likely.
The event is at McIntyre Hall in Mount Vernon
2501 E. College Way, Mount Vernon, WA 98273
To get there, take I-5 and get off on the college way exit, number 227 and proceed East (If traveling South, turn left; North, turn right). You'll then travel along College way until reaching the hall. It's just past the intersection of La Venture on the left-hand side. I'm betting you'll be able to see the protests easily.
Show up with signs, cheers, whatever have you. It should be interesting to say the least. Expect a photo journal after the event. This will be exciting, to say the least.