It sounds like you already have an MVP, awesome.
Now you need some evidence that people want to pay for it. Make a landing page from your MVP which shows visitors its main exciting features. Have a link called 'Learn More', which leads to a form asking for user info (name, email, etc.). To make it even more attractive, you could tell them their first month's free, or 75% off when they 'sign up'. Data from this will give you a form of validation that will be useful for investors, it will give you a list of first clients, and it will give you some training in how to get the site into search results. Once you've got this, or some other form of evidence that it will work, start talking with investors.
You should start by 'pitching' to just friends first. They don't have to be potential investors, it's just to get feedback. Then pitch it to strangers (maybe your neighbor, people from relevant Meetup groups, whatever), then to investors you're closest to (maybe you're connected to some on linkedin?), then to investors you don't know, etc. At each of these stages you'll be getting more and more confident about how to effectively promote your product, you'll be working out bugs, and you'll be perfecting your pitch to get the most interest. By doing it in steps you're not putting all your eggs in one basket, and you'll instead be increasing your chance of getting investment as your approach bigger and bigger investors.
Some seed stage funds include First Round, Freestyle, Boldstart, Homebrew, etc. Send me a message for a more thorough list. To save time, find investors with portfolios that do not include any failed products similar to yours. Otherwise you'll be wasting time, and it's actually important to do all your fundraising in as short a time period as possible (it looks bad if it's drawn out too much). Also to save time, get in contact with the Partners at these funds. You can try going through companies that they've previously invested in.
Best of luck, and let me know if you have any other questions,