I tend to use a lot of Cognitive behavioral therapy and Dialectical behavior therapy with these presenting problems, which many times consists of worksheets and talk therapy to help clients change negative thought patterns and "re-train" their brain to view their world through different (more positive) lenses.
There are lots of great resources out there. Here are some examples to get you started: Blurt: Increasing Awareness and Understanding of Depression
Blurt is a blog dedicated to discussing depression and the experiences of those who have it. Here is the link: https://www.blurtitout.org/blog/
UnF*** Your Brain
A podcast and website focused on CBT-based techniques to help manage symptoms of anxiety/ depression.
Besides the app, they also have a show on Netflix named "Headspace: Guide to Meditation". Calm App
Both Headspace and Calm offer a free 7-day trial period but they charge afterward.
Insight Timer App
A free app for anxiety, depression, and stress