Build it and they will do absolutely nothing.
You need to let people know about your business. Specifically, the people who need your product/service.
Now there are several ways to find them, but we'll focus on low-cost methods for today.
Content Marketing
The more that customers must know about your product before they are comfortable buying, the more they'll first seek educational content on it.
And they'll do that through Google/Bing/Baidu which will take them to blogs.
Blogs are how companies educate and engage potential and exisiting customers for free.
However most blogs are terrible. Most marketers fail to realize that quantity is not substitute for quality. This has conditioned consumers to skim content for highlights. Focus on quality to stand out.
Write about the problems facing your target customers. Presumably, you know more about the industry than your potential customers. This means you should be able to provide insights on subjects they care about.
Social Media
Find communities where your target customer hangs out and become a contributor.
If your customers congregate on a Facebook Group, join the group and participate in discussions.
If your customers live on a Reddit subreddit, join the subreddit and participate in threads.
Once you’ve found conversations that are relevant to your business, you can start to engage potential customers and share your expertise.
Make sure to add to the conversation without disrupting it. If people are sharing and commenting on articles related to your business, look for opportunities to share your perspective. If people ask questions you can answer, offer your help.
Do not promote your product renlentlessly!
Only suggest your product when the need for it comes up organically.
This is a great method to learn more about your target customers and their problems.