Well to start off you can flirt with a boy you like. You can ask your friends but things like playing with you hair while staring at him is flirting.
You can also start talking to them. Just talk about whatever. It doesn't really matter as long as you seem friendly and maybe make them laugh or laugh at their jokes or whatever. Just make them feel good.
Also touching them helps to connect with them. So something like a light punch on his arm when he says something funny or a high five is good. If you start to get to know him better then you can do more stuff like hugging and other things.
"I get really nervous when I talk to people I don't know... Witch makes it hard to make friends not to mention boyfriends" - Humm... Can you name the "Witch" who makes it hard for you to get a boyfriend?