Welcome first of all.
how she might like leave me for some one she likes better cause i mean i guess this is more fear talking but since she is activly out looking for other relationships i mean i worry she might find someone she likes better and i end up second string or not at all
If we talk about poly in this case, you can be at ease. What describe would be the behaviour of a monogamous person, as this person would fall out of love if a new love interest comes along. A poly person just falls in love again without loosing the feelings for the older spouse(s). So rest assured, if your partner feels polyamorous, she won't leave you because someone is 'better'.
Ending up second may happen though, especially during the initial phase of the new relationship. We call that New Relationship Energy and this can lead to her neglecting you because of the new and shiny relationship she just developed. She needs to be aware of that and work on herself to not treat you unfairly.
Also another thing is I get kind of afraid to talk to her about this stuff afraid I might slip up and say something stupid or something else you know and how like i feel this way about this but i dont want he to think i am telling her to not do it just well i guess that is another thing how do you guys come to compromises with stuff when it comes to things involving polyamry and other thing
Talk to her about your fears, she should show an interest. Poly doesn't work (as most relationships don't work) if the partners don't learn to talk about their needs, wishes, fears, ... with each other. There is nothing wrong in stating "This or that doesn't sit well with me. I want to find an agreement concerning our handle on it in the future."
You will find many threats on boundaries around here. Try a tag search for "boundaries" and see what comes up. It's all about setting the stage for this relationship. You need to feel secure, loved and content with your relationship with her, otherwise things will blow up in your face.
cause it feels like she is just saying this is what i want and is letting me know and there is no room for well any sort of conversation or compromise
Especially this shouldn't happen. You have every right to express discomfort with the situation, as things are new to you and one needs some time to wrap the mind around it. And she on the other side doesn't have the right to expect you to function otherwise and apply a 'sink or swim' approach.
You really need to sit down and talk to her. Explain what is making you afraid, why you feel insecure and what your questions about the things she herself imagines are. If you don't speak up, things will not get better. You won't be able to be OK with your relationship miraculously over time. This needs some effort and work to function for both of you.
Wishing you luck and strength for your way.