Help looking for jobs

Me and my brother (24 and 19) are currently looking for full time jobs, preferably retail or office and neither of us have post secondary education. I am very confused on what to do and am seeking assistance.

Where do i look to find job postings? Like how do i know which canadian tire/gas station/hotel/pharmacy/office/etc is hiring and which isn't? Is it absolutely best to bring resumes in person or do online applications sometimes work?

I would really appreciate some guidance since we're not from Ottawa, i have lived here on and off for the past 5 years and this is his first time living in a city. We are from a very small town where things work completely differently so its hard to navigate things sometimes. Thank you in advance :)

Edit: Just wanted to say i haven't replied to any comments but i've read and considered every single one, the stress has been heavy and today i was spiraling so i didn't have energy to reply but i appreciate every single answer, you guys have helped so much i am eternally grateful