well if you want to bottom, start by getting yourself loose enough with your fingers, then work your way to a butt plug and/or dildo, use a smaller one and then work your way up, and as for a cock, find you a more experienced guy, I would not recommend anyone who is new to this because of his nerves, and he would not remain hard enough to do any penatration and it will be as much of a let down to not only you but the other guy as well, take your time, use lots of lube, and most importantly Use a Condom.