Lots o' tips here: How to insert a massive amount of timed photos in your video, what a YouTube channel trailer is, where it lives, how it works, why you want one, end screens, and how to decide to invest the time in a trailer for your channel.
6:10 in the video shows the insert timed photos trick if you just want that.
Live and learn. The title of this video was "Create a Spastic YouTube Channel Trailer in 10 Minutes" and thanks to viewer comments, I found out "Spastic" in the EU is a very derogatory term. Opps!