Hiragana and katakana begin to be learned in Japan as soon as you enter elementary school. Kanji is essential for learning Japanese, but I think you should start with hiragana first. I'm sorry if I didn't get a reply.
@Chefboyman カタカナ is used when writing foreign words, names that derived from other countries, and onomatopoeia. The use of ひらがな is for grammatical particles, and all Japanese names and words that are made in Japan.
If you have already memorized both ひらがな and カタカナ then you can start learning basic Kanji, like the ones that they teach you in elementary school in Japan. But I would focus more on learning how to form sentences and learn how grammar works in Japanese.
Reading books and watching videos that were made for an English speaking audience. Dedicate time to watching YouTubers that make the content you enjoy in Japanese in English. Over time, you'll notice your improvement. Cartoons are great as well. The process should be fun. Every time I finish a light novel or a show I was interested in, it's really fun and I know I'm getting better.
Be conscious of the common mistakes people make while trying to learn the language you're interested in.
For example, I'm still learning Japanese, but here are some I see all the time: Never learning to read hiragana and katakana Never learning to read kanji Having no idea what は and が do
Some really common English learning mistakes I see: Not being able to tell L and R apart even in text ("Please correct my daily" instead of "diary" I see this at least 3-5 times every day on HiNative alone) Directly translating Japanese to English Forcing slang and idioms into your speech despite not understanding them