Actually nevermind I can see on the first comment that you’re on android.

There is currently no way to add an address on Organic Maps.

But I do recommend downloading a app called “Every Door” 
I screen recorded a video to possibly help you know what to do. I also tried to show the places where I tapped but if you’re confused send me a message!

https://files.catbox.moe/e6y57u.mp4