How do i impress a stoner girl?

The same way you impress any girl. The fact that she smokes does not change how you go about impressing her.

Your chances at what? Getting laid? Being friends? Developing a relationship? Actually, it doesn't really matter. For any of the above, why don't you just keep talking to her and being friendly. That always seems like a good first step. Then maybe simply ask her out. If she is new to the area as you seem to indicate, she might appreciate someone to sit with at lunch time. While sitting around at lunch chatting, ask her if you can have her phone number in order to call her or text her.

I don't know who this "they" people are, but it might not include her. Until you text her, you don't know for sure she won't respond. If she doesn't, it does not mean she is not interested in you. It could simply mean she was busy at the time, just did not hear her text alert and didn't see it until much later or even that she doesn't like texting back and forth (some people don't.) If she does not text back, try calling her. That is where you punch in her number using the numbered buttons on your phone and then hit the call button (it is green on my phone.) It will ring on her end and if she hears it, she will answer it and you two can actually speak back and forth just like you were face to face. Cool, isn't it?

All kidding aside, you never know unless you try. Not every girl refuses to answer texts.

Good luck.