Hi there,
you should unzip the package on your mac and the upload the unzipped folder to
root/packages via ftp. Then you log in to admin your page.
Go to dashboard/extend/install and scroll down until you see your block. There should be a white button next to it with the text install - press it and finished

Take care you upload only the inner folder to your ftp. To explain, most packages come in a folder inside a folder;
like after unzip a folder called x-slider;
inside that one there's again another folder called x-slider; when you open that there's the folders inside like blocks, helpers, tools, ... and some php files and so on
make sure you upload only the inner folder