Well actually the only thing you need to type is the computer name and domain...
You can also rerun the discovery task - or that's a problem in your scenario? It is meant to be run periodically.
In fact, it is meant in such a way that you can create a Discovery Task chained with a Deployment Task. The Deployment Task would be set to run on a dynamic computer group that contains all computers without avast installed (dynamic computer groups are enclosed in normal parentheses ( ) in task target definition). You'd then schedule the Discovery Task to run e.g. every night and it would automatically install the software on all new machines...