In the traditional sales page you leave your customers only the options of a) leaving your page or b) buying your product. The problem is that most people won't buy your product the first time they visit your page. However there is a way to repeatedly try to sell a product to a visitor even after they leave your page.
The way to do this is with an auto responder. An autoresponder allows you to save contact information of the visitor, usually there first name and e-mail address. You can then e-mail them at set intervals.
To get an autoresponder you will either need to purchase and install a script onto your website or use a third party service. You'll probably want to use a third party service if you're new to autoresponders.
You will need to create a page were visitors can enter their contact details. If your using a third party service they will probably give you the html code which you would then just copy and past onto your page.
People generally dislike advertisements so don't make your e-mails look like advertisements. Include useful information and figure out a way to include your product and link to your product in the e-mail.
Most people are reluctant to give their e-mail address away. In order to get them to give it to you you'll need to give them something in exchange for them giving you their e-mail address. Some things that you could give away are free tips about whatever your product is. Or you could buy a free e-book with master resale rights and then give that away.
People don't know you so they don't trust you. You need to build that trust by giving them relevant, interesting content to show that your helpful and informative.
You should also try to use these three design tips
1) Use a heading in a slightly bigger font and different color from the rest of the page. 2) In bulleted form describe two or three benefits of joining your opt-in mailing list. 3) Your main goal is to get people to subscribe to your mailing list. Use words like "Send me the free tips" on the submit button of your form.