Any tips or directions to hang things where there is no stud ?

You need to get some wall anchors and screws...they can be found at your local hardware store...because your mirror is heavy, I would hang it using 3 screws/plugs to share the load

We hung a 40 lb wall clock on a wall by first testing the weight (these are plaster walls with no stud behind where we wanted to hang clock) we used metal plate things that could be screwed in, in several places. I would recommend fastening your mirror with at least two of these plates which we bought at Home Depot.

How heavy is the mirror? Do you know how to find your studs? they are usually 16" on center, measure out from the corner and use a stud finder to locate your stud.

Then I would get a French Cleate long enough to at least fasten into one of the studs for a heavy mirror.... and use a toggle bolt for the hole through the drywall..... https://www.amazon.com/s/ref=nb_sb_ss_i_3_12?url=search-alias%3Daps&field-keywords=french+cleat+heavy+duty&sprefix=french+cleat%2Caps%2C220&crid=1J1S18SRTSQYE

I personally would not use the screws with the plastic anchor, cause I've seen them pull out. Toggle bolts.... https://www.amazon.com/s/ref=nb_sb_ss_i_3_11?url=search-alias%3Daps&field-keywords=toggle+bolts+for+drywall&sprefix=toggle+bolt%2Caps%2C235&crid=1EASU9OPZJAS2&rh=i%3Aaps%2Ck%3Atoggle+bolts+for+drywall This will require drilling a hole big enough to fit the folded toggle to fit in the wall, once it in the wings come open.... https://www.youtube.com/watch?v=dXlDDsPzpf4

Screw in anchors or toggle bolts.

https://www.lowes.com/pd/E-Z-Ancor-50-Pack-1-25-in-x-0-5-in-Standard-Drywall-Anchor/1042133

https://www.homedepot.com/p/Crown-Bolt-1-4-in-x-5-in-Zinc-Plated-Mushroom-Head-Toggle-Bolt-Anchor-2-Piece-00461/202187088

There are Toggle bolts rated for 75 lbs. I would use one of those. The ones with plastic zip ties that anchors the toggle to the wall are nice and easy to use.

😊