Add the lines in the alias file to ~/.aws/cli/alias. These will take effect immediately.
cvt - validates template on local disk
dse - describe stack events; prints nice table with logical nresources with associated status
instances - list table of EC2 instances including Name tag, status, and IP addresses
active-stacks - list of stack names that are not in DELETE_COMPLETED. The name is a bit of a misnomer. Change it to something to is logical to you.