Q: how do i know what is in the other part of my hard drive so i can delete and make room on hard drive

We don't know, we don't have your computer in front of us.  Do you have an external drive?

If you mean the "Other" category shown in About this Mac, please read the description of what kinds of files will be listed as "Other".

OS X: What is "other" space in About This Mac? - Apple Support

Since the Other category is a catch all for anything that does fit elsewhere it is almost impossible to use Other to do any cleaning.

Instead I suggest you download and install OmniDiskSweeper. When you run it, it will tell you the names of the files and folders which are taking up the most disk space on your disk drive. Once you know that then you can decide what you can delete and what needs to be moved.

You first step before starting this task is to backup everything first.

The storage report lists 6 categories, 'other' is one of the 6. Anything that is not in a category with a name, is 'other'