I was reading the overrie partial on the docs and was trying to override the posts componenet of the rainLab.Blog plugin. On my theme i created: partials/posts/default.htm but the content was not overriden. Can someone pinPoint my error?

Instead of /posts/ you should use the alias name of the component. So if you have given it a name of myPosts then you should place the partial in partials/myPosts/default.htm

Thanks that was exactly it

Full instructions with screenshots on how to override partials of the Rainlab blog plugin here

Thanks @info14532