There are much better fishermen than me on this board who have better experience and answers but I'll take a whack at this one.
WHAT - Yes, there are salmon in the rivers of Washington/Southern BC in the summertime. You have spring chinook that are available (getting pretty long in the tooth now however). Also, the big rivers Fraser, Skagit, Snohomish, Columbia will hold salmon in the summertime. Check the regs and this board for guidance.
WHERE - As above and as always with specific spots, check the local tackle stores, do some exploring, talk with guys on the river but typically summer salmon like deep water with slow current to hold in. For summer run steelhead given that you live in Redmond, I'd reccomend the Sky or the Green as being great rivers to concentrate on and learn.
HOW - Both bait fishing and fly fishing are effective, in fact summer steelhead are a great fish to improve your fly fishing techniques. Shorter casts, often clear water so that you can really understand what's going on and how the fish react. Bait fishing works well, it does require some pretty light gear to be consistently effective. Look for cloudy days or some rain and action can be very hot.
Bank fishing is an absolute option on the smaller rivers (in fact it's preferred as long as you are in shape and can walk a while). On the bigger rivers that hold salmon bank fishing restricts you to a few spots but is still effective.
Hope this helps and Good Luck.
_________________________
"You're not a g*dda*n looney Martini, you're a fisherman"
R.P. McMurphy - One Flew Over The Cuckoo's Nest