I did...
"achieve yourself Latin" <- I suppose you mean "achieve fluency in Latin"?
Well, I mean, once you become fluent in one foreign language, then it's no big deal to become fluent in another to some degree of correctness. I mean, the mental process necessary for the fluency is similar: at the beginning you need to be creative, you need to be able to say something with the words, vocabulary and grammar you control well. More creative you are, better you can express yourself even with a limited "mental resources" for that language. More frequently you do it, bigger "dictionary" of "ready to use" phrases & grammatical structures you build for yourself and easier it becomes to use them again. Later on, you find that most of your creative 'creations' (pleonasm) were, in fact, unidiomatic, and "unnative" while maybe grammatically strictly 'correct' and you start composing sentences in the target language not by creativity but by a clever combination of your previous knowledge of native phrases and idioms, so in the result your text (with some a mistake here and there) may look and read quite native.
Anyway, for starters, you need to be able to compose grammatical Latin sentences. My recommendation for a beginner is to take some beginner's Latin text (if you read the Lingua Latina Per se Illustrata book, that is quite a good source), translate it as best as you can into your native language and then translate it back without looking to Latin. Compare the original with your translation, find serious mistakes, if you count too many of them, attempt the translation again and again until you achieve a reasonable perfection.
And then be creative... read a lot the native litterature (Roman litterature for Latin; but some Erasmus won't hurt either), use the phrases you have learnt in your own compositions, and so on and so forth.