Hi there and welcome to surfing-waves
An 8' Bic is perfect for beginning to surf on, especially if its a friends, as chances are you will 'outgrow' that board pretty quick in terms of ability. After you've picked up the basics you will have a better idea of whether, eventually, you want to move up or down in size in terms of boards. A very simplified version is the bigger the board, the easier it will be to learn on.
Have a search on this site and you will find heaps of topics on board lengths, widths, styles etc. It depends on a whole heap of factors including the types of waves you will be surfing, how regularly you will be surfing and your current fitness levels. Go with the Bic for now, you might find that you are a natural and outgrow that board in a few weeks or it might still be perfect for you in two years time. Have a search on this site, and on others and if you can, talk to as many different surfers as possible. Go and talk to people in surf shops if you can, but dont believe everything they say, remember that they are there to make money.
Good luck and happy surfing and searching
