Thinking about adding a half bath in basement

Hi all,

I am sketching ideas for finishing the basement and it makes sense to add in a half bath. I'm a novice at this and I am having a hard time visualizing how the sewer lines will connect to my main line out of the house. I would think that with the current position I won't be able to tie into it and obtain flow via gravity. I've attached a picture for your review and am willing to listen to any and all ideas.

Thanks!
Jason