Using Converter to Import other mods.

See this post to see where to start. Essentially it's impossible to simply convert a mod and have it be playable like that. You will need to be somewhat or very experienced in Oblivion/Morrowind modding depending on what you're trying to do or willing to learn it. There are also things that cannot be automatically converted. Bows and arrows are part of this. Also some clothes won't look right and many meshes will need retouching, collision added or changed etc. Nothing that's impossible to learn but it takes time. Quests and scripts mostly aren't converted and at best 50% of dialogue is. There's also the trouble of getting permission from the original modder if you're ethical like that. However you won't get banned if you don't get it and decide to release it here.

That's because the converter can only handle certain types of spells - specifically those with magic effects also present in Oblivion. This excludes spells with levitation, scripts, detect keys etc. You will have to either manually delete all spells with those effects from your mod or change their magic effect to something else.