Are you saying you'd be grateful to help some or that you'd be (or you are) grateful for someone's help? I'd be happy to help you.=I want to help you. I'd be grateful for your help.=Thank you for offering to help me (that is, thanks in advance for the help you will give me in the future). I'm grateful for your help.=Thanks for helping me (present) OR Thanks for having helped me (past). Of course you can always just say "Thanks. I appreciate it." Less formal and more versatile.

None of those are correct. If you are asking for help from someone: I would be grateful if you can help me. If someone has already helped you: I'm grateful for your help.