Attached Link: http://www.safehaven-uk.org/p5lighting/index.html

If you are using a gel as in a transmap, you need to plug it into the light's intensity node. If you mean a gel as in something with adds colour and texture to the light, then you need to plug this into the colour node, as SamTherapy suggested. The attached link may help make things clearer.

---

"you are terrifying
and strange and beautiful
something not everyone knows how to love." - Warsan Shire