I found an HTML blog template under the MIT license, and I would like to convert it to a WordPress theme and sell it (for example, on ThemeForest). If I understand correctly, the MIT license will allow me to do. Do I understand that correctly or not?
The MIT license says:
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
Modifying an HTML template so that it works with Wordless would be a a form of modifying the software, which is explicitly permitted. Any such modified software must include the original copyright notice and the MIT license statement itself.
It would be usual to indicate the nature of the changes, to include a copyright notice for the modified (derivative) work, and to indicate the license being granted to this modified work. (There must be some license to the modified work or no one can use it.)
Anyone can create and sell such a modified work if they comply with the original license by including the original copyright notice and license text.