You can generate contribution statements for all of your donors from the Donations by Contact report. 

Be sure the date range at the top of the page is correct for the statements you'd like to generate, then click the Extra Actions dropdown and select whether you'd like to print or email the statements.

If you choose to print the statements, you'll see a popup window with your customization options (shown below):

Set your preferences and then click the green "print" button (displayed above). This will download a single PDF file to your computer containing the statements for ALL donors - one statement for each donor. 

If you choose to email the statements you'll see a popup window with options to customize the emails that will be sent to donors. 

For more detailed information on this process please check out this article on Generating Contribution Statements.