Inspector doesn't show the public...please, help:)

hi, i’m trying to make a Flappy Bird game following a tutorial but in the inspector tab even if i write “public” in the script (C#) it shows just the name of the script. i’ve read some other questions but the answers didn’t really help me… can you tell me how to fix this?
oh and i don’t know if this should happen, but when i press new project it doesn’t show some packages, but just the ones i’ve downloaded, but in the trailers i’ve seen they say that there are some packages already available… but this concerns me less… thank you a lot for your time!

for anyone instrested that has the same problem: in my case i (stupid!) didn’t save the script and there was an error. if there’s an error in the script hte inspector won’t show the public (i’m telling this because i didn’t know before this question)