1. Once you have uploaded your new documents navigate to the Document Library you placed them in. 
2. Click the button that says "All Documents" towards the top right of the page.
   
3. Select the "Checked Out" view from the list.
4. This will show you all documents in that library that are Checked Out to you.
5. You can click on each file and check them in individually, click the toggle button at the top of the list to select all documents or pick a selection of them with the toggle next to the file name.
6. Once you've selected the files that you want to check in, click the menu button at the top of the list and click Check in.
7. You can now click the view button and change it back to All Documents to see the library in the normal view again.