Starting an apparel brand and selling $10,000 worth of product per month is a significant undertaking. Here are a few steps you can take to get started:

1. Develop a unique and compelling brand identity. This includes creating a brand name, logo, and visual style that will be used across all marketing materials.

2. Research your target market. Identify who your ideal customers are and what they are looking for in an apparel brand. This will help you tailor your products and marketing efforts to meet their needs.

3. Design and source your products. Work with a designer to create a line of products that aligns with your brand identity and resonates with your target market. You'll also need to find a manufacturer or production partner to produce your products.

4. Set up an online store. Choose an e-commerce platform like Shopify or WooCommerce and build a website to sell your products.

5. Market your brand. Use social media, email marketing, and other tactics to promote your brand and drive traffic to your online store. You may also want to consider working with influencers or collaborating with other brands to get the word out about your products.

6. Continuously monitor and optimize your business. Keep track of your sales and customer feedback, and use this information to continually improve your products, marketing, and overall business strategy.

It will take time, effort, and resources to build an apparel brand that sells $10,000 worth of product per month, but with hard work and dedication, it is possible.