The best way to learn anything graphics. Is by watching how it is done with your naked eyes. Search on Google for tutorials, you will see some videos sample coming from YouTube.
Or you can search directly from YouTube channel instead. There's lots of people that will be teaching you how to do it. Stick or follow those ones that you believe is making sense to you and follow what ever steps they applied.
Learning it online may take time and money, so you have to be consistent and have more Internet data. To save money while learning please subscribe to MTN or Etisalat night plan.
The subscription is not much compared to the normal subscription.
Where you may have problem is getting the Adobe illustrator software. Purchasing adobe products is quite expensive. But if you can afford that. Go to Adobe website or look for someone that will help you with the Adobe raw file and download it in your system.
It won't be easy for a newbie. But you have to try.