Writing songs for movies and TV could be a very exciting and rewarding career. If this a route you want to follow I would recommend that you do some research on music publishing as well as sync licensing. Sync licensing is the process of putting your songs on film / TV. Another piece of advice would be to connect with other musicians and producers via social media so you can get an idea of what works for them. Also, try to find and follow music supervisors on social media, they are the ones who select what songs get placed. One last suggestion, follow the following hashtags: #musiclicensing #musicpublishing #musicsupervisor #synclicensing. Oh yeah of course make sure to write and practice often. Best of luck to you.