what does the phrase “It’s fine to celebrate success but it is more important to heed the lessons of failure.” mean

Which two sentences are written in subjunctive mood? take this money and go buy some clothes for yourself. i was happy because i passed the test, which i studied for. if only my umbrella would fix itself, then i could go out in this weather. i'm going on a trip to canada, but i'm not taking you with me. if i were the thief, i would have turned myself in before i got caught.