Scared to go and race motocross?

ok, dont get me wrong i LOVE motocross and i will do what ever it takes to win, but its just the fact that when i start and i go onto the track ill just be embarrassed if i loose and if everyone laughs at me? something like that. has anyone ever came last in a race and been laughed at before, some people are really cocky about when they come first and you come last, any tips on how to just not just care what any one else thinks? also im riding a 1999 KX 100, and im also embarrased if anyone says anything about my bike, im 13 i pay for my own things for my bike, my family does too but i contribute still and i cant afford to get a 2008 for instance or something, it doesnt look like a 1999 more like a 2003, so can anybody help me? Very much appreciated thanks you :)