You have to improve your knowledge and don't give up when you have still write a wrong sentences. You need more understanding about the definition of sentence, fragment and clause (and differences of each other). After that, you can look types sentence structure.
Understanding the definition of sentence is one of the important step before you learn the types sentences structure. Let's go to the link later about definition of sentence.
Sometimes the learners are confused about clauses and fragments so they have to learn the differences of them. You can learn the materials in the link later.
After that, you can write a paragraph and an essay with types sentence structure effectively.
Click and learn the materials on the link below!