Two easy ways to immerse yourself with content created by native speakers in your target language:
1) Listen in your target language whenever possible (via audio books, movies, tv shows, and podcasts). I like podcasts best.
2) Read in your target language. Major news sites and blogs will most likely exist in your target language for free. And you maybe be able to buy books (fiction or non) written by native speakers as well.
You can supplement those two with working through exercises in a grammar book of your target language.
Obviously, if you have a native speaker to practice speaking with, do so, but the listening and reading suggestions alone will get you very far. I'm immersing in Spanish right now, and this is working well for me.