Ma'am I know which colleges are giving the diploma courses in urdu but I am asking how to apply for this course?
You can apply to those colleges either through their official websites. Each college has its own official Website. Go to the official page and search for admission forms/application forms. If you are facing any difficulties you need to contact the college either through online helpline numbers or email IDs or you can fill offline forms by going to the college itself. Address can be found on Google. I suggest if you are not a very technical person then you should take help from your elder siblings/parents/mentors.
Hope this Helps!