CBD is easily absorbed by the skin so you just need to massage it into the affected area. Before putting the cream on, make sure that the skin is clean. Wash the skin first with soap and water thoroughly. It should be free from any other ointments or creams that may prevent it from penetrating into the skin. Doing this will make the skin absorb the cream faster.
Pharmacology published a study in 2016 looking at medical marijuana for migraines, specifically in relation to its effects on serotonin, with very positive results. You’ll notice that neither study looked at CBD in isolation from other cannabinoids (which is an issue with a lot of research on CBD and pain). Truthfully, the research on CBD alone just isn’t sufficient to make any pronouncements about its effects on headache pain.