Open up Adobe Illustrator on your computer and choose File and then New. You should automatically be set up for an 8.5" by 11" page size. In the Name field, insert whatever you would like to call your document and then click OK to view your new document.
Now select Edit, go down to Preferences and select Units and Display Performance. If you are doing this on a Mac computer, then choose Illustrator, Preferences and then Units and Display. You are doing this to change the default preferences from pixels or points into inches. Once the box has opened up, change the General menu to inches and click OK.
Then select the Tools palette and choose the Rectangle tool. On the canvas of the main document that you opened before, hold down the Alt key (or Option key if you are working on a Mac) whilst clicking the mouse at the same time. In the Rectangle dialog box that appears type seven in for the width and five in for the height. Using the selection tool that appears, move the newly appeared rectangle to the top half of the page.
Now you are going to open the Borders Decorative library by selecting Window, Brush Libraries and then choosing Borders Decorative. With the rectangle artwork selected on the top half of the document, browse through the different styles and colours of borders and choose which one you like.
A little tip is that you can browse loads of different line styles that you can apply to the rectangle border on your document. You can do this by selecting the Line Library shown in the Brush Libraries menu when you select Window.
Then you just save your border document as you would any other file.