I sit alone at lunch and I what to the easiest way to meet new friends I can sit with in the future

Have you always sat alone?

Since 9th grade

Start setting with other people and talk to them during lunch.

Talk to other students between classes.

You need to make the move to sit with other people.

but how old are you, what level school ?

you are talking about tattoo and strip clubs in your other posts,

I'm 18 and I'm in 12th grade

Why do you think you eat lunch alone?

I don't know I always had trouble making friends since I was little

Do you have favorite classes and teachers? Do you know other students, or are most of these kids strangers to you? Do you have a pet? a hobby? a favorite video game?

I know some but most of them are strangers. I have 2 dogs. I watch Netflix most of the time watching Dexter. I don't play that much

I think making friends boils down to 3 things in general:
1. Be friendly and natural without trying to impress
2. Compliment the other person on something you really mean, anything from what they are wearing to how they spoke in a class
3. Make the conversation about that person rather than yourself. Ask harmless questions about what they like or how they feel about some music or teacher or anything. Get them talking without being actually nosy. That way you aren't self conscious. When you do talk, keep it short (like me too or I did that once or I sort of feel that way) so that it's more about the other person.

You could start by sitting near someone, remember to ask if the seat is taken.
Try to sit near a class mate so you aren't a complete stranger, and this might give a topic of conversation like a recent lecture.
To be friendly, be interested in other people and get them to talk about themselves
Try to notice something about them before you sit down so you have something positive you might engage them with