The first step you need to take in order to sell ads on your website is to create a page with all the details that anyone interested in advertising might need. Once you have made this page, link to it from all other pages using a link description such as 'Advertise with us', 'Advertise on this site', or 'See your ad on this site' etc.

What needs to be added to this page is discussed here:

Introduction

The page should begin with what the advertisers will gain from advertising on your website.

Create a Media Kit for Advertisers

Create a Media Kit with information such as your site's unique visitors, page views, visitor country and so on. In addition to this, run a survey on your website and collect user demographic information like male/female ratio, their incomes, their educational qualifications (grad, post grad, college etc) and so on.

Once you have this data, create a Media Kit for your advertisers. The media kit should explain -

1. Your website's description and its target audience

2. User demographics and site statistics

3. Ad Specifics and rate card (What type of ads will you be accepting? Banner ads? Sponsored links? Ezine ads? CPM or flat monthly/weekly rate, ad spots, availability)

4. Accepted Payment Types (Credit Card, Paypal, Check etc.)

You can publish the Media Kit in PDF format which can be downloaded or simply type all the above info on this page for interested advertisers to see.

Contact Information

Do not forget to mention an email address where interested advertisers may contact you if they have any questions unanswered.