To declare a major or minor in Linguistics, you first need to find an advisor who will help you find the best courses for your interests. Any of our Linguistics faculty members can serve as your advisor: just go to their office hours to talk about it.
To declare a minor in Linguistics, you just fill out the Declaration of Academic Minor form [pdf].
You can leave these forms in the mailbox of the Director of Linguistics (in Tucker 112), who will scan them and send the originals to the Registrar.
The forms ask you to indicate the specific courses that will count toward your degree. Those courses are entered in DegreeWorks. Often you end up taking different courses, though. During your senior year, you may have to fill out a Petition for Change in Program form so that DegreeWorks counts your courses correctly.