It is common and an excellent practice to link your website to your Facebook page. First step is to create your Facebook page. Next, decide where you want to add the icon. The sidebar is a common location, since it is visible no matter what page on your website your users are on.
There are several versions available--horizontal, vertical, etc. (see attachments). Choose your preferred logo and download it to your computer.
Navigate to your site, click Create/Edit > Edit Sidebar. Once in edit mode, you'll want to add the Facebook icon. Click on the image icon in the editor, and then the upload link. Locate the icon, double click it to upload to your library. Once the icon is in your library, choose the "Insert" link to add it to the sidebar.
Now, open a new tab and navigate to your Facebook page. Highlight and copy the url.
Back to your website, with the sidebar still in edit mode. Highlight the icon you inserted. Now, click on the link button in the editor (looks like a chain and globe) and paste in the url you copied from your Facebook page.
Save.
Voila! Great job.