I'm still single. help!

I'm a 20year old guy who had never kissed any girl on the lips; only on the cheek. I'm not very confident with myself when talking to girls cause I overthink of situations all the time by jumping out the future and predicting what's going to happen and the things I should do, and when this happens I notice I become more nervous so I told myself I'll stop thinking and just go with the flow but that way of thinking doesn't remove my self anxiety. My real question is how do I become good with speaking to girls and find a girl who can be my next girlfriend??? I know everyone will say "be yourself" but I need more something specific, such as if there's a silence on a conversation how do I recover and continue talking.

I'm really becoming desperate now cause all my friends had been in a relationship and I haven't not even once,in addition I'm in my 20's now.

Go with the flow is the right thing. The thing is you have to stay in the now. Fear is because you're in the future. What if?
Past and Future doesn't exist in this moment in time. So anxiety is caused by negative self talk and the worry. What do you do for you anxiety? Meditation works good for that. There is self guided meditation on you tube for anxiety.

For what to say, just find what they're interested in, and learn something about it and talk about it. Learn new topics, or find interesting subjects. What do you think about this?

20 is very young, so you have lots of time to find the right girl. Don't be in a rush. Just enjoy making friendships with girls, and keep light. If it's supposed to happen it will happen. You don't have to force it, and don't have to do anything special. You'll know what to do when the time arrives, and you'll be comfortable.