Syntax is how to arrange words and phrases to create sentences in your language.
You need to choose which order the words go. There are six different ways you can place the words, from most common to least common: SOV,SVO,VSO,VOS,OVS,and OSV. S stands for subject, the word that does an action on the object, V stands for verb, the action that the subject does on the object, and O stands for object, the word that is acted on by the subject. English, for example, is a SVO language(I see him).
You also need to think of other things,like whether or not adjectives go in front of nouns or verbs they describe. You can also use articles, like "the", "a", and "some".
Basic Latin Word Order by latintutorial on youtube.com