I've never hung wall paper, the trimming part scares me, suggestions?

Lots of videos here. Copy and paste the link in your browser.

https://www.youtube.com/watch?v=drcqCH2wv48

That's easy. Use a small snap-off knife and be sure to keep your blade really sharp. Push up against the ceiling with a 6 inch drywall tool and cut into the crack. Use that same tool and hold it straight up on the baseboard and cut into that . Main thing, sharp blade. You can do it.

Home Depot (I think Lowe's too) have free classes for projects like that. Videos or nice but having a professional right there to ask questions is nice.

I would agree with others here. Look at videos and invest in special tools that help trim edges. You'll find that straight edges are pretty easy with a little experience.

I was taught long ago before you tube from an elderly neighbor. She taught me so much but there's 2 things I still do to this day. At the top of the wall right at the ceiling, use a thumbtack to hold a long string with a weight at the bottom. Use this line, you can actually make small vertical lines along this string and use this as a guide line to hang your first strip. Of course they sell a chalk string to do this too.

A sharp blade is your most valuable tool. You will need a straight edge to cut. At the baseboard hold up the straight edge on the top edge cutting the paper on the side closest to you.