Dosing in Homeopathy is very simple.
A quick guide to dosing:
Children under 12: 6c Potency
Older children and adults: 30c Potency
Frequency: If it's a very strong cold, or flu, you can dose 3 times per day until there is a change. Then back off.
Long term problem? 1 dose per day for 30 days, and watch for changes.
Then take on an as needed bases for a few days.