The IC section is where you would describe the ritual as if you were talking to another character. So it can still be quite technical, but don’t include OC logistics. You can include what kind of roleplay might be involved like, “Offer a flagon of ale to the Dark Ones” or whatever you’re trying to achieve.
The OC Section wants to include all your OC logistics. Things like Item IDs if you’re casting something on an item, or OC specific phrases like “Will be in effect for the rest of the PD event”. Make it clear what you expect from the ref/plot team.
Pro tip: Don’t make a ritual that needs a lot of work from the ref team on short notice. Either write into your ritual that you’re going to notify them in advance of casting, or that you don’t expect an answer from them immediately (“A response will take a day to be delivered” or “be delivered at the start of the next PD event”).
Spend time reading published rituals, and also speaking to covens and magicians of the realm you’re trying to work on. Your idea might already be tried, or you might be able to avoid some previously discovered pitfalls.