Hi MeliosAdorialis, welcome to Chicken Smoothie!
Like Woodwolves said, it is completely fine to share computers, staff doesn't care if several accounts use the same computer - as long as none of them exists just to benefit another player, all accounts should be owned by real, separate players. As long as you trade fairly with your friend, you will be just fine.
Also, just saying, you can take off the message from your signature, it does nothing. ^^; Admins don't care about them and it will not have any effect. It doesn't matter who owns the account if it only exists to benefit some other account - on the other hand, if you are a real separate players playing fairly and by the rules, you have nothing to worry about. ^^
Your friend will probably be helping you out as well, but here's some links that might come in helpful:
Chicken Smoothie WikiChicken Smoothie HelpGuide IndexNewbies Click HereMust read topics for newbiesIf you need any help, you can contact any of us
General Helpers. :]