Gabdhaha, an update to your question. We do issue certificates once you have completed the course if you are subscribed to Commonlounge Pro. You can learn more about the Pro offering here: Commonlounge Pro.
Steve Krug's book "Don't Make Me Think" is considered a classic amongst UX Designers. In the following four tutorials, we'll go through the least you can do today to make your website a lot more usable. It's a good way to jump into the field, and once done, you'll already feel like you can start making contributions to improve your site's UX.
This is a list of about 20 short, crisp tutorials on UI Design — once done, you should have a good understanding of what the field of UI looks like, have a good understanding of principles of visual design, as well as know a bit about the tools you can use to create your first mockups.
The Sprint Process is a UX Design process first introduced by Jake Knapp and John Zeratsky. It's a five-day process for answering critical business questions through design, prototyping, and testing ideas with customers.
The following short list will introduce you to the Sprint Process. If you want to learn more about UX Design, check out our UX Design List.