Decide on a topic for your column by considering topics about which you're familiar and about which the community may wish to read. Ideally, select a topic that isn't otherwise covered by the newspaper's staff. For example, local politics is likely covered, so the editor may not desire to have a community member write about politics. Though your column idea can be geared toward a niche market, it's effective to develop an idea that has a broad scope.
Write a pitch letter describing your proposed column idea, the reasons why the column would be of benefit to the newspaper, the frequency you would hope to write the column and your requested fee, if applicable. If possible, provide sample topics for three or four columns, too.
Update your resume to highlight your writing experience. If you've previously written a column for a newspaper or had other writing jobs, make sure these details are evident in your resume.
Write a sample column, if possible, or provide some samples of your writing. Because electronic submissions are convenient, scan any hard copies of your writing so that an editor can read them electronically.
Send a short email to the editor of your community newspaper asking if the publication is currently accepting applications for community columnists. Explain that you have attached a proposal, a resume and some writing samples to the email, and ask that the editor take a moment to review your submission in the near future.
Call the editor a few weeks after sending him the email if you haven't heard back from him. He may still be considering your application or perhaps hasn't fully read it. A follow-up phone call will jog his memory and show him that you're keen on the column idea.