Answer 1

Maybe your account isn't activate yet so check your email to activate your account

Answer 2

KANNA

Increase your level then you will be able to upvote. Some features are blocked for new user to avoid spam.

Answer 3

it is always hard to give up things.
Dont worry.

Answer 4

If you activated your account but still unable to give upvote thn you can mail to sololearn [e-mail]