Hello @pearlmultimedia,
Thanks for asking. 
I checked your website and the link you have shared and it seems that the spacing is coming because of section padding. Let me share a screencast to illustrate the point.

Now, you have mentioned that already margin property has been adjusted. I think you haven’t activated Advanced Mode under X > Settings > Permissions > Administrator > User Preference > Advanced Mode and select Always On.

After that open the post and relevant sections to adjust padding property. Here is a screencast to help you out.

After adjusting Section paddings you need to adjust Image, paragraph and heading margin to further optimize the spacing. Here is a screencast to help you understand. Please adjust the margins and spacing should fall in place.

Although not recommended but if you want a custom CSS option to adjust the spacing, please add following CSS under X > Theme Options > CSS:
.single-post .x-section {
padding: 15px 0 !important;
}
.single-post .x-text img {
margin-bottom: 15px;
}
.single-post .x-text p {
margin-bottom: 15px !important;
}
.single-post .x-text h2 {
margin-top: 10px;
}
If you would like to learn CSS, I am sharing few resources that you take a look to get started with CSS and an interesting tool that you can use to speed up the development process.
I recommend you to watch following video that will help you to get started with CSS.
https://www.youtube.com/watch?v=MFR4WXiLzpc
Sometimes it can get a bit difficult to find out the right selector to be able to write the required CSS codes. A handy tool that can help you in this is Google Chrome dev tools. I am sharing the resource that you can refer to get started with dev tools.
https://developers.google.com/web/tools/chrome-devtools/css/
https://developers.google.com/web/tools/chrome-devtools/
https://www.youtube.com/watch?v=tP_kXBJWPhQ&t=200s
Thanks.