There isn't one. Just download the full 1.8.0 package and upload the files to your MyBB root, then head over to /install to run the upgrade process.
What about my forum data? will I lose everything
If you follow the steps in the
Upgrade Guide properly, your forum will not lose any data. The most common mistakes are generally not uploading the files correctly or failing to disable plugins before attempting the upgrade.
Yeah but the problem is I already have a forum so if i download the full package of mybb 1.8.0 and stick it in ftp it will overwritev all my files including themes,config.php etc. it will just overwrite and install a whole new board no?
Changed Files Upgrade
If you're just one point behind the newest version - for example, if you're using 1.6.3 and the newest version is 1.6.4 - then you can use the changed files package. This is available in the blog post announcement. If a changed files package is not available then the latest version of the software should be used.
Before upgrading, you back up your forum. That means backup up the database. It also means backing up any graphic of language file or anything else you changed and don't have backup copies for. When I do it, I just back up everything in the forums folder system. Better safe than sorry.
When you upload the files it will overwrite the existing ones. But your messages, settings, etc. will not. They are in the database. But you should back up the database anyway, just in case something goes wrong and you need to revert.