I have a idea about new social networking platform that come with new features to connect with people. I already built the prototype/demo web app.
I'm 20 years old from Sri lanka. I have little knowledge on some technical areas. Good at php, java etc.
I have developed some other ideas too.
1 non-profit organization (online platform for crowd funding), networking softwares for educational institutes etc.
I like to connect with a cofounder from USA (business side).
Please give me some advice.
Most possible social networking platform ideas have long since been exploited and have been taken over by the giants. Unless you 1) have something that is better than what you can get from Facebook groups, Instagram followers, Discord+Twitch, and 2) have already secured about $10 million in hard funding to pay for the kind of coding, design, and especially marketing support, you are fighting a real uphill battle. The "Gold Rush" days of social media startups getting millions in Stupid Money dumped on them for having some half-baked idea are long gone, I'm afraid.
Best advice? Build your feature. Make sure it works. Take it out into the real world. See if people actually want to use it - that is, it solves a problem that they have. If it does, it will start to get traction. If it does not, take it back to private status and do some more work on it until it does.
My advice is to stop focusing on your age or location. Instead spend your time researching any one of your ideas to validate the need, test your assumptions, and to build a plan. Co-founders don't typically connect around just an idea, they need to have a real plan, based on solid information, and do the work that would minimize risk for a business partner.
Starting with a product is almost always a mistake, because it's unlikely you have tested your assumptions, developed a marketing strategy, or validated your audience's interest.
As you said, you have an idea. What you need is a plan. You may discover that you're more suited to finding someone who needs your help rather than in finding someone who can help you. It's not certain either way.
There's nothing in your message that tells us what is unique about your idea. In fact, it sounds like a few "me too" ideas. So, you're really going to have to do the planning work to demonstrate that your idea can become a business.
What are you looking in the cofounder? technical side or business?