The Professional Association of your field of study will usually have an annual conference. Finding your Association will also link you in with:
The conference of that association is where new research is presented. Academics apply to present and are chosen by a peer group.
Often there are undergraduate research sessions. This is another place you can take your poster. The conference proposal page (Call for Proposals) will include many details about desired topics, presentation parameters, best practices, etc. Follow these to the letter.
It's valuable to join your association as soon as you can. Most have student rates. Many conferences will include grants for costs to attend.
As an example,
The American Anthropological Association will hold its annual meeting in November. Their webpage includes the Call for Proposals, which details they types of presentations they encourage, the themes, and logistics of each.