With regards to creating a portfolio, I would suggest the following website --
This website talks about process; you may also want to obtain the book version by the same name. As your undergraduate degree is not in architecture, do not feel you have to submit architecture; submit creative work --
Contact the graduate programs to which you are applying and see what they say.
Look at examples on https://issuu.com/home
A portfolio of student and professional work is required of all applicants demonstrating the applicant’s abilities in architectural design and communications. Examples of work should include undergraduate design studio work, sketches, free hand drawings, construction drawings, photos of architectural models, and digital models and drawings demonstrating the applicant’s abilities to use architectural graphic programs such as Sketchup, Sketchbook Pro, Rhino, and others. Portfolio content should meet the following minimum requirements:
- Show at least six  undergraduate design studio projects completed as a student.
- Show introductory analysis, conceptualization, project context, and project development as well as final products for each project entry. A short narrative must accompany each entry.
- Demonstrate two- and three-dimensional design development
- Demonstrate increasing complexity across the projects
- Demonstrate increasing attention to detail development of the design across the projects