I cut the four openings on my sample/trial card by hand with a razor knife, but that was terribly time-consuming, so for the other 50 (yes, I made 50 -- I have a long Christmas card list!), I cut two long oblongs with my die-cutter, then pasted a bar across the middle! That way I only had to cut two openings, and it saved me lots of time to use my die-cut machine. I don't know if that will make a difference to you in posting, as it wasn't done exactly from your pattern, although the result was the same.
After cutting out the openings, I made pin pricks at the corners of the windows, so I could line up my cutting of the straight lines at top, bottom, and middle. I also ran white card through my Big Shot machine with a snow embossing folder, then cut shapes to layer in front of the house. When the blue parts were pasted together, I mounted that on the front of a white card, and the inside had only one word - PEACE (don't we all need that!) - stamped and embossed in silver on the navy card bits left over from the window openings. The house was stamped and embossed in red, and the trees were die cut, with a bit of pearl gloss to represent snow.
After I had them all done, I thought I should have run the window layer through my wood-look embossing folder, but oh well!