Rei has some great blog posts about getting into backpacking: https://www.rei.com/learn/series/intro-to-backpacking
This article in particular goes over all the basic equipment with recommendations: https://www.rei.com/blog/hike/beginner-backpacking-gear
Depending on where you are headed to in AK in September (Hiking the Chilkoot trail vs. a backcountry trip in Denali etc.) recommendations will vary slightly.
Hope this gives you a place to start.