I was accepted in the 42 program in Fremont (programming school), but they offer no help for getting a Visa. So I want to know what are my options as a Canadian to stay in the US for long period of time. I already spent one month this summer at Fremont. Can I just be there 5 more months, come back to Canada, and go back after a unknown period of time?
No, you cannot study unless you enter the US in F-1 or M-1 status. As a Canadian, you do not require a visa, but your entry to the US is still classified according to the same system, and you must still qualify for that status.
To qualify for F-1 or M-1 status, you need a document from your school called an I-20. Your program says it offers no help getting a visa, which certainly means it does not issue I-20 forms.
Since you'll be unable to qualify for F-1 or M-1 status, you would be admitted as a B-2 visitor (that is, as a tourist). Tourists can enroll in short courses of study only if they are incidental to the purpose of travel, which is not your case. For more substantial courses of study, here's what the US government has to say:
Special Instructions for B-1/B-2 Visitors Who Want to Enroll in School
Is it permissible to enroll in school while in B-1/B-2 status?
No, it is not. The regulations, at 8 CFR 214.2(b)(7), specifically prohibit study in the United States while in B-1 or B-2 status.
Before enrolling in classes, individuals who are in B-1 or B-2 status must first acquire F-1 (academic student) or M-1 (vocational student) status. Enrolling in classes while in B-1/B-2 status will result in a status violation. Individuals in B-1 or B-2 status, who have violated their nonimmigrant status by enrolling in classes, are not eligible to extend their B status or change to F-1 or M-1 status. These regulations provide no exceptions.