The spring before your senior year, you want to identify a faculty member to sponsor you: they become your thesis advisor

By August, you will write a proposal for your research project

In fall of your senior year, you enroll in the first of two honors thesis courses (while working on your research project; being supervised by your thesis advisor)

In winter of your senior year, you enroll in the second of two honors thesis courses (while working on your research project; being supervised by your thesis advisor)

You likely finish the project (and revisions) in spring quarter, submitting the final well before you graduate

If you plan to apply to grad school (or already did), make sure you also submit your final thesis to the Lofland award to bulk up that CV! Also note that completing an honors thesis is the only way to graduate with high or highest honors