Goodness. I've been going through AskSeddit trying to help some people out and I keep seeing this style of post. You know who you are. You all keep answering your own questions in your own titles and then prattling on about meaningless backstory that is largely irrelevant. A few examples:

How do I tell her I'm interested?

You tell her you are interested with words out of your mouth and actions of your body.

I want a relationship. How do I talk to her about it?

You tell her you want a relationship and then the two of you will talk about it.

How do I set up a second date?

You invite her on another date.

etc. Maybe I'm in a particularly cynical mood but sometimes these self-answering questions just seem so silly that I can't help it. If the backstory of your post is anything along the lines of, "I met this girl at some place at this time and I like her but idk if she likes me but I want to go out with/bang her; help", your story isn't unique and has probably been discussed before.

EDIT: I'll include a bit of actual advice along the lines of u/mharris717's comment. The point here is that virtually everything you do when it comes to women carries some level of risk and there is no such thing as a "shortcut" or "magic pill" or "perfect line" or whatever that will get you into the pants of any woman without the possibility of rejection. You WILL be rejected and you need to be confident enough in yourself to move on. There are plenty of other posts on that subject to look through as well as "Models" by Mark Manson which everyone on here should read before posting anything.