A list of all client computers (which have the client software installed) is available in the default group section under machines.
To send the package you need to create a task, select the target machine (this will show you same information as held in the machines section), select that you want to deploy an ai package and select detail of which ai package it is (you must have create an item under the ai package section of the configuration resources section in the console).
I don't mean to be critical but you really need to read the AI section of the manual as it is often not as simple as just sending the package to a client. In most cases you need to have used the package builder to strip out the machine name of the machine you originally built the package on). Then you also often need to use the task to transfer additional files, run scripts etc in order to make sure your package works on any machine you deploy it to.
Hope this helps