I’ve carried my bike in the trunk of the car a few times. I have a Honda Civic and I have to fold the back seat down in order for the bike to fit.
This video is pretty good on how to take the front wheel off and put it back on. It doesn’t cover disc brakes (which it looks like some Sirrus bikes have):
https://www.youtube.com/watch?v=UxgneYfegNc
It looks like the Sirrus has flat handlebars, so you’ll probably need to loosen the handlebars and turn them 90 degrees in order to get the bike in the trunk. This video on how to straighten a crooked handle bar is the best I could find on which bolts you’ll need to loosen and then retighten:
https://www.youtube.com/watch?v=XldqMDNx7Gc
Give a shout on the forum if you need help. Lots of folks here that would be willing to meet up with you and walk you through it.
Welcome to biking and the forum. If you’re looking to ride with others, I highly recommend the Google calendar of all things bike related in DC which can be found at freezingsaddles.com Since you’re new to biking, I’d also recommend taking a class on how to fix a flat tire. REI and a few of the local bike shops usually offer these classes for free.