You don't need a computer or any software to learn how to draw. I would suggest you learn how to draw first, then you can think about learning software. Software is certainly useful for graphic designers and illustrators, but the skill comes before the software. Software is only a tool, and a tool in unskilled hands is practically useless. If you give me a scalpel, I know that I can cut things with it, but that doesn't make me a surgeon.
Have a look at "The Beginner's Fashion Design Studio by Christopher Hart". He also has a youtube channel. I have no affiliation with Christopher Hart or the publishers. There are numerous similar publications and youtubers with amazing drawing tutorials on the subject.
Once you have a drawing, and if it's already good enough quality, then it's possible to just scan it and use that as your artwork.
Alternatively, you could learn how to use graphics software to ink and colour a scanned rough sketch. I would recommend vector image editing software if you want to create line art. If you have money to burn, then Adobe Illustrator is excellent. If you have no money, then Inkscape is free and Open Source.
It's also possible to draw/paint using raster image editing software such as Photoshop, or free and open source software such as GIMP, Krita or MyPaint, but then you'll probably need a graphics tablet and stylus, because trying to draw or paint with a mouse is a hopeless task.
Note that design software such as Adobe Illustrator, Adobe Photoshop, Inskcape, GIMP and Krita all have a fairly steep learning curve, so be prepared to spend quite a lot of time learning them.
There are also lots of drawing apps available for iPad or Android tablets, so that's also another possible route.