To get an idea of what a thesis is, we might begin by noting that the Greek word θéμα = thesis, subject, topic - refers to the process of placing or laying-down in the sense of taking a position or proposing something. Thus, a thesis presents your position on some topic in your field of study, and it therefore includes argument (presenting evidence) and, where appropriate, critical examination of opposed positions on that topic. Unlike the typical research paper, then, the thesis will present and defend a view that is distinctively your own.
At an even more general level, we could say that an Honors Thesis is an opportunity to work closely with a faculty member on research that brings to a conclusion your undergraduate experience. Though it is the biggest thing you will do as an undergraduate, you shouldn't think of it as an overwhelming project. You will most likely find it to be the most exciting, fulfilling and rewarding experience of your undergraduate career.
The first step in writing a thesis is to contact your academic advisor, or any other potential thesis advisor, early in your junior year to discuss your ideas and interests. Needless to say, any faculty member in your department might also provide suggestions on securing a thesis advisor.
The links in the right column will act as your guide throughout the process. On it, you will find important dates, people who can act as guides, a schedule of workshops, the official guidelines for constructing your thesis for publication, and other helpful information.
Enjoy the academic journey!