Hello,

I read some of the earlier answers and all of them are pretty technical. I don’t know why people give complicated answers to a very simple question. If you want to start learning logo designing. Focus on few things:

1. Try to make icons, symbols or character with very basic shapes such as rectangle, square, circle.
2. People prefer iconic logo so try to add 2–3 elements into one single meaningful mark. (in the attached image, I made an aeroplane with one corner of letter D)
3. Learn how to play with letters, it will benefit you a lot. For above three points check this as an example:

Once you realize that you are good at these things then you can study design principles, color theory, typography in order to get better as a professional designer. Always check if your design is following these 5 things:

Image Source: Google

Thank You.