You should now delete the install directory from your web server.
2. Secure the Writeable Directories
It is advisable to move the attachments, downloads & templates_c directories (which need to be writeable for WHMCS to function) outside of the publically accessible folder tree. Instructions for how to do this can be found in our documentation @ Further Security Steps
3. Setup the Daily Cron Job
You should setup a cron job in your control panel to run using the following command once per day:
4. Configure WHMCS
Now it's time to configure your WHMCS installation.
We have lots of helpful resources & guides available to assist you in setting up & using your new WHMCS system in our comprehensive online documentation located @ http://docs.whmcs.com/ (you can access the docs at any time by going to Help > Documentation or using the handy Help shortcuts available from most setup pages within the admin area)