Hiya! I’ve personally done student visas in the UK and work permits here in Canada, so maybe I know something helpful.
For the visa part:
Here’s the link to the Canadian Immigration page for students: https://www.canada.ca/en/immigration-refugees-citizenship/services/study-canada.html
It looks like the requirements vary slightly depending on if your friend will be an adult when they enter Canada, and if they’re going to Quebec. Follow the instructions on this website carefully. You will need to pay a fee (looks like $150 for adults) and you will need to have paperwork from a University saying you’ve been admitted, proof that you can pay the University’s fees and support yourself, and it looks like Canada also requires something called an “attestation letter” which says that you’ve been allocated a student visa spot by the province.
For the University application:
I don’t actually know the Canadian system. When I applied to the UK, I just looked at the university website and followed their instructions. Personally I would look up the rankings for Canadian universities - doesn’t have the top one, but make sure you’re applying to reputable universities (I get the feeling there’s some scammy universities that exist mostly to get money out of international students, and I generally think 2-year bootcamp type places for programming are not as good as a standard degree.)
If you like Vancouver, I believe UBC has a solid reputation and they have info for international students on their admissions page Applying to UBC 
Follow the instructions on the University website - if you have questions about the application process, you can call the University’s admissions office.
Other things to think about:
Check if the University has an “international students office” or similar. If so, they can be very helpful with “how does stuff work in this country” and “how do I get my visa extended” types of questions.
Another thing: big vs small university can be very different experiences. Large universities have more resources and can offer more stuff, but it’s also easy to get lost in a crowd. At smaller ones, you can get to know faculty & staff personally, and it may be easier to make friends. This is mostly a side-note, but it does occur to me that larger universities may be more used to dealing with international students.
Work experience: I’m not sure about the rules in Canada, but when I was a foreign student I was only allowed to work about 20 hours per week, which is enough to do a part-time job on campus, but not enough for a full-time summer internship or a co-op placement (co-op programs, where you work for a whole semester or more, are common here in Canada). Going into programming or biochemistry, it will be extremely valuable to have work experience, but companies typically aren’t going to do work permits for student interns. If you’re applying to universities that offer co-op programs, you may be able to ask admissions or the international students office how that works for international students.
General advice:
Most of the visas I’ve done have been at the airport on entry to the country, and I’ve typically found the process pretty easy - the key is to make sure your paperwork is complete, and have it together and ready to hand to the agent. Don’t be one of those people who can’t answer basic questions like “where are you going to be studying”? (Though I’m American, so I’m aware I’m playing on easy mode.)
If you get accepted, you’ll also want to think about things like making sure you have access to money + phone service when you get here.