For All themes You can download new themes separately that are listed here and then follow these insrtuctions to upload them to you server:
1. Click the Theme Download button.
2. You will get the .zip extension file.
3. Right click this JBlog.zip file and then select Extract Here.
4. You will get a JBlog folder, now upload on FTP.
5. Upload the bin and Theme Folders.
6. Login in your admin section.
7. Click on presentation tab.
8. Now select ur snap shot and view new Theme.