Question: I can come up with a scene and totally picture everything in my head like a movie but I'm having trouble adding detail to things so others can picture it and making the page longer because right now I can have something that could last a whole chapter but it's only a paragraph long because there's not enough detail. How can I work on that?Answer:
The secret lies in specificity.
Take a look at the following article, and try applying the technique it recommends...
You'll find that not only will specificity make your chapters longer, it will also make your writing more powerful, more vivid, and more emotionally involving.
This is especially important for major events that you want the reader to fully appreciate. Specificity gives your reader the experience of being there.
Of course there are times when you can summarize things briefly, for instance when you just want to make a quick transition to the next important event. Good writing should always leave out the boring bits--which are the bits of no significance.
It is also possible to have too much specificity. For instance, if you are including details which it would be unrealistic for the character to notice or which the character wouldn't have the vocabulary to describe. (Choosing which details to include helps you delineate the character.)
However, your problem is lack of detail. So give the specificity exercise a try.