Small window for ads video

My channel has live videos and I want to display some ads video. But I don't want to interrupt user when they watch live video (user would be frustrated if they miss 15 or 30s content while watching) so I'm thinking a way to display a small window for ads video (I have integrated Roku ads already) in the bottom right corner while playing the live channel but don't know how to do that. Any suggestion would be appreciated.