It would help if we knew which model of Kindle you have but you will have the option to view the "Archive"/"Cloud"/"All" list of all the books you own and download the books from there, assuming the books are compatible with that particular device. Not all Kindle books are compatible with all devices.
Alternatively, you can use a browser on a different device (Computer/Phone/Tablet) to go to your Account and "Manage Your Content and Devices" and send the books from there by clicking in the "Actions" box alongside the titles.
I ordered two books and didn't notice that it said "deliver to second Kindle". I don't have a second Kindle. How can I get those books delivered now?
First off - you are buying books for your ACCOUNT. It does not matter what device they go to - you can always read them using your account.
Second - you may want to check your Amazon Account using the Your Account button top right of every Amazon web page.
you need to do something like My Account / Confirm Account Details / Manage Content and devices / click the DEVICES tab - look at the various devices registered to your account and delete any that are no longer relevant.
you may also want to click on your chosen device and confirm DEFAULT so that stuff get downloaded their first.
You may also want to take a few minutes and read the USER GUIDE that came pre-installed on your Kindle so that you can enjoy the many benefits and fun things a Kindle and an Amazon account can do for you.