Do read the resource centre, especially about cycling.
Media is what is inside the filter, which includes sponges, ceramic balls, ceramic noodles.. this is where the bacteria live.
"Seeding" is when we take *some* media from an existing set-up and put it into a new filter to help with the cycling. It is impossible to tell how much you would need for a new tank and how much bacteria live in your friend's media.
I suggest, you do a fish-less cycle, but seeding your own filter. It will be useful for you to understand and see how a fish-less cycle works in practice, there is a lot you can learn from it. Seeding the filter may speed it up by as much as a week or more and you will be able to go straight for your final stocking that way, instead of only being able to add 1-2 fish every week.
If you post your tank dimensions and your tap water parameters, we will be able to help with the stocking.