I'm not sure how well a microwave will work to make edibles... Definitely don't leave it on unattended, if you're microwaving oil or butter it'll start flying all over the place in no time x).
Since you mentioned shared accommodation I'm assuming you are at university and don't want to get caught making edibles in the shared kitchen... Instead of using the microwave to make edibles which may or may not be very effective, I'd recommend making cannabis milk instead! Normally I put a 50:50 mix of full-fat milk and water on the hob (about 0.5L of each) and bring it to a boil, decarboxylated weed goes in and you let it sit in there occasionally stirring for about 30-45 minutes. You can add a clump of butter or some cream to add extra fat for the weed to dissolve in. Since smell is an issue in common areas for you I'd suggest to get a cheap kettle and do it in your room instead... Towel the door, burn some incense, keep the kettle on the window sill with window open, etc to reduce suspicious if you are really worried... The kettle wouldn't hold a constant simmer like the hob, but I think you can still get it to work. The heat just serves to facilitate the THC dissolving into the fat, instead of simmering just turn the kettle on to bring it to a boil. Stir the contents for like 5 minutes and switch the kettle back on to knock the temperature up again. Do that for 30-45mins, strain out the weed and drink the liquid!
Also for a first timer, I'd recommend not to take too much your first go with edibles! The high is quite different from smoking. It takes a while to fully kick in but it lasts a long time, overdosing on edibles can leave you feeling quite miserable for a long time if you're not comfortable being really high. I normally chuck in 0.3-0.5g of weed (very high quality) for mild to medium strength kind of high.