I want to write for a fashion magazine

Start by reading. I'm sure you've already covered this step but find four or five fashion magazines that you like and really read and study their writing styles. Find the ones who publish writing that fits your style and check their submission guidelines. If they accept freelance work there will be information in the masthead about who to contact with your query. Be sure to have your article more or less written when you query and don't write anything with time sensitive material because your first query could take a few weeks to get a response. The reason for having your article written is your query should say what the article is about, give an approximate word count (within about 100 words), outline any external sources you have (or will) used, including interviews and reference books and offer a date for when you can turn in your final, ready-for-publication draft. Once you get a response to your query you will have a very short window in which to get your story to the proper editor (most likely the one who read your query but sometimes it will be a different editor). Some magazines will require that freelancers only send publication ready articles, others will require their own editors proof your work before it goes to print. This is another good reason for having your story more or less written before even submitting your query letter.

there are books at the library that list magazines that allow submissions of articles, my suggestion to you is to go and have a look and make a list of the magazines that interest you. also, i believe on the net, you can also find similar lists of magazines that call for submissions.