I'm very bad at learning languages is there anyone who can help me learn Polish?
Don't give up. Learn every day and use your language every day. Read, listen, speak with native speakers, write. Do all that regularly. Don't try to memorise the cases. Memorise phrases that you want to be able to use which use the cases and verb forms. Study grammar when you need it. Learn vocabulary that is important to you. Don't try to learn every word at the beginning. Be patient, it will take time - especially if it is your first foreign language. Understand that you are not bad at languages.
If you are a native English speaker - you can subscribe to Polish-Englisch Topics of the Duolingo Forum and ask for Polish native speakers learning English and looking for people like you. ;-)
I suspect, most of people on this English - Polish topic has the same problems as you. ;-)
You shouldn't focus on the grammar too much at the beginning. It is really a lot and hard to learn, I'm a native speaker, I can use it but I couldn't explain probably most of it to someone who does not speak polish. I think you should get familiar with the language first and slowly try to learn and understand grammar. You also should not give up if you do not understand something like a grammar rule, that is totally normal and it takes a lot of time to learn a new language. You also always can use this forum to ask for help if you have any questions