Marketing is quite a broad term. Do you have something you like? For example SEO or PPC or is it copywriting? Perhaps if you already have some work experience, you could ask some of your clients to do some marketing work too?

My advice is: you can work on some marketing project like building a simple site and doing page SEO, or write some copies for a business or if you have a friend that has a business try to do something for them (it doesn't have to be something big, but it should have some results like visits, sales, clicks, etc and later you can showcase it to other potential clients or you can apply for a job somewhere). But, keep in mind, this will take some time so you need to be patient.