I hope you are well today and thank you for your questions.
1. How do I add a picture in the ‘About me’ section?
As described in the following page.
2. How do I add thumbnails next to the ‘recent posts?’
It seems the thumbnails are not displaying because you are using default recent posts widget and not Activello Recent Posts Widget that displays thumbnails.
To help us keep support thread separates could you please create new thread for each of your other questions here Activello - Colorlib Support Forum instead of asking them in your single thread as it makes the thread messy and hard to read.
If you want to you can also add reference of this thread in your newly created thread.
We would be more than happy to help you on your new thread.