Hey,

B.Des is bachelor in designing which is a 4 years full time Undergraduate course. The minimum eligibility criteria for this course is that you must have completed 10+2(higher secondary) with a minimum of 50% aggregate score.

You will have to give entrance examinations conducted by various institutes. One of the best institute for making a career in fashion industry is NIFT. Another institute is National institute of art and design,delhi  which is a government institute.
To know more about details for admissions in NIFT in the link below:

https://www.google.com/amp/s/design.careers360.com/articles/nift-eligibility-criteria/amp

Hope this helps!