Designing is a purely creative process. In fashion, you take all that creativity and put it in the form of an outfit. You can start by drawing out whatever comes to your mind (clothes or stuff that's completely unrelated to fashion are all fine!) Then, for example, if you love horses, and you really want to create your own t-shirt, you can try combining the two of them together, etc. You could combine two fashion styles together, or add on to what's 'in' right now. You could even take two or more 'out' items and make them into a new item! Fashion is creativity, style and imagination.