First, do you want to wear women's clothes? Second: There doesn't have to be a reason, but there may be. Such as Cross Dressing (CD) for humiliation, sissification, punishment. I wear women's clothing because I 'feel' like a woman, & want people to relate to me as a woman, professionally, in business and socially. I enjoy crafting my own style from the myriad of offerings of women's clothes, compared to the limited men's styles.
To learn something of women's clothing, just read all the ads in the papers, especially the Sunday edition where the big department stores ads come out. What ever is for sale is what women are wearing. Half the population is female, and they are all wearing women's clothes. Look at the clothes--not what's underneath--and focus on what you think you'd like to wear. Narrow the selections to a few items because you have to start with a couple things first.
Acquiring some clothes: First you need to find out what size you are for various garments. Look on line at women's clothing sites and find a sizing guide. That's a good start. When you're ready to buy you know where to start. On the cheap, try used clothing stores such as Salvation Army, or Goodwill. Easy to find a try-on boot, and there are no pushy clerks who hover over you thinking you're a perv for trying on women's clothes. I suggest you start with the skin: get a bra and panty, a slip or half slip. Most women wear pants now. It's easy to buy a woman's pants. However a new cross dresses is going to feel better with a skirt & blouse or dress. Shoes: problem depending on size of foot. Women size is men +2. If you wear a 9 men look for 11. Few women's shoes are larger.
I have no experience with sissy, forced fem, adult baby clothing. If you want that I suspect it's all on line.