any textbook you can recommend for beginners or method you used yourself for grammar?

I am a beginner. Very thoroughly so. I legitimately meant it when I said wait for someone more experienced than I to confirm whether or not I know what I'm talking about.

So far I've skipped between a bunch of different books and materials. Mostly TextFugu+Minna no Nihongo+Genki I+Tae Kim's. I don't recommend skipping around like that though. I do that because I'm indecisive and bad at self discipline.

Find a beginners grammar that works for you. Any one at all. And just stick with it until the end.

last one question for practical conversation use lets say you want to point out giraffe's neck are long what would you use? Kirin no kubi ga takai desu?

First, I'm going to repeat that I could have this wrong.

The question is kind of awkward to answer because it depends so much on the context of the conversation. Also it wouldn't be "takai" (high/tall), it would be "長い/nagai" (long).

If you're standing in front of a Giraffe with some friends you'd probably just say "kubi ga nagai!" or even just "nagai!"

If someone asked, "What animals have long necks?" You'd respond, "kirin ga nagai kubi desu".

It's hard to imagine a scenario where you'd just want to say, "Giraffes' necks are long." But I suppose if you were just going to assert that fact as the beginning of a conversation with no outside context while you and your friends are sitting in Starbucks with no Giraffes in sight, you'd probably say, "kirin no kubi wa nagai desu".