Congratulations! Inline skating is a very fun activity. Alki has to be one of the best places to skate in the whole country.
I don’t know of any instructors, but I’ll share with you how I learned. I just strapped on skates and pads and found a smooth/flat trail and just started practicing. You’ll probably spill a couple times but at slow speeds it shouldn’t be bad. I would rate my agility as about average and within one hour I was confidently skating down the trail. It really isn’t a difficult activity if you take your time and start out slow.
Stick with it – it’s a great time!