if you use ftp client like filezilla then
you can just select the plugin files at your computer and drop them to ftp window of your MyBB forum
here is the plugin files uploading method in different words !
basically
plugin files are to be added to inc/plugins folder of MyBB files server.
if plugin consists of single
php file then that is the
simple method. but plugin might
consist of several files. in that case we have to
follow folder structure of plugin files.
this can be confusing at sometimes as plugin coders may not follow unified method to
pack their plugin files.
readme file if exists with plugin can consist of the instructions
if plugin files are located in a folder named
Upload then
its contents should be transferred
by following folder structure. that
Upload folder itself should not be transferred.
after adding the plugin files you have to visit admin panel >> configuration >> plugins
page to install & activate newly added plugin. then proceed to configuration >> settings
page to find the settings related to newly added plugin and setup the plugin settings.
youtube has some videos to help (you can search for
MyBB plugins installation)