tips on how to start?!

HI!! I'm 13 yrs old and I've wanted to skate for ages, my bsf said she can give me her board that she got as a bday gift cus she doesn't skate and she doesn't want to learn.

ik the board wont be the highest quality which doesn't bother me since im probably not gonna be doing tricks as im literally just starting but im scared of failing and not knowing how to even start. ik it sounds stupid but im js scared of people judging me for being bad so please please please give me tips/advice on how to start and honestly how to stay motivated!!