You use MiKTeX Package Manager (MPM) to install and remove packages.
The package manager can be run in two modes: batch and windowed.
MPM runs in batch mode if you specify command-line options
mpm(1) for a list of available command-line
If you do not specify any command-line options, MPM starts in windowed mode and will see a window similar to this:
Select all wanted packages in the list view.
Click onto install the packages.
For example: you want to install the memoir package:
Locate and select the memoir package in the list view, e.g., type the key sequence M E M O I R.
You can now clickto install the package.
Sometimes you don't know the name of a package, but you know the name of a file that belongs to the wanted package. In this case, enter the file name (can include wildcard characters) in the filter edit box.
For example: you need the file
musxflx.lua in the filter
The list view will be reduced to contain only the
musixtex package. Selecting
musixtex and pressing + will
install the package.