Door Replacement

[Chess]

So I've been living off grid in my school leave for a couple of years on a homestead we haven't been traveling anymore and I want a regular door rather than a school bus RV type door. Well that and my door kind of got ripped off a while back so it'd be nice to have a replacement now... Can someone point me in the direction of good tutorials on here and or YouTube videos of removing the actual dang door so that I can begin building a frame in the recessed area? Also is it possible to build a frame with hinges without doing any welding I'm thinking of making a sturdy steel frame rather than something out of wood if possible. Ideally it would be something that dogs cannot break through from the inside getting out nor goats breaking through from the outside in.