I am a 25 year old male from Serbia. I've lived here all my life and I wish to move. I've already researched information regarding migration to Canada on a work visa, however there is one main thing that I'd like to inquire about. Do I need a valid job offer upon arrival in Canada in order to get the work visa or can I just search for a job when I get there? Will they grant me the visa without having a job offer? Can someone explain please?
You can't apply for a work permit without a job offer.
The first step is to find an employer in Canada who is willing to offer you a full time job. That employer must then obtain approval to hire a foreign worker (this is something called an LMIA). To get an approved LMIA the employer first has to advertise the job for at least a month to prove that no Canadian could be found for the role. Next the employer has to submit the LMIA application for processing along with a $1,000 fee. Processing typically takes 2-4 months. If the LMIA is approved (not all are) - you can then applied for a closed work permit that will be tied to that specific employer and job.
So your first step is to find an employer in Canada who is willing to offer you a full time job.
Not the only way - you can also obtain a visa without a job offer depending on your work experience and education - realistically you need a masters degree and a couple of years work experience. you should be able to find the relevant info on the CIC website.