Q. How to put a refrences on a scientific poster, if all my information is collected from a single website and this website has the information

If you only used that website, you need to provide only one citation. No need to copy/paste their reference list.

This is a sample of IEEE citation for a web site:

Author(s)*. "Title." Internet: complete URL, date updated* [date accessed].

M. Duncan. "Engineering Concepts on Ice. Internet: www.iceengg.edu/staff.html, Oct. 25, 2000 [Nov. 29, 2003].