You may add images into your Nova posts and even into the bios although for the bios, I recommend using the image galleries.
HTML Images at W3Schools has everything you need to know about using HTML image codes so I am not going to repeat it here. This page will give image size and other guidelines.
In order to add images, you will need an image host (Photobucket, IMGUR, etc.).
You can upload images to the server for use in your bios, tour images, or gallery images. Select the type of image you’re uploading and the image and click upload. Currently, uploaded images can be no more than 1280KB in size and cannot be larger than 1024×1024. Please try to be as consistent as possible with your image sizes.
Nova Post Banners
Banners (i.e. images at the beginning of a post). In general, this is hard to give specific sizes on because you do not want the image to overflow the edges of the allowed page area. You also want the banner to be wide and narrow. As a general rule, and this will vary, the max-width should be approximately 950px and the max-height 425.
Nova Post Images
If you want to add an image into the post to demonstrate a visual, you may use a banner size or you may use a square size. I do not recommend using the higher than wide images (rectangular) unless you are willing to also add text alignment guides to your image code.
Recommended Size: 400px x 400px max.
Bio Image Gallery
Lead images should be perfectly square or rectangular (higher than width). Wide banner style images will not appear correctly in the character index card.
Nova’s Height and Width are set to 1024px X 1024px. I would seriously prefer that you keep your images between 975px – 1020px (max). More importantly, make sure all of your images are in the same size range so that paging through your images is smooth and generally pleasurable for the viewer.
If you are going to use non-character images in your bio gallery (i.e. images of character’s weapons, tattoos, family members, etc.), you need to add the caption to those specific images so people know what it is. You’ll need to do this in Photobucket, IMGUR or whatever image manipulation application you use.
Image File Names
I am going to be a total bear on this one.
RENAME YOUR IMAGE FILES OTHERWISE I WILL DELETE THEM!
Make your image file names short and very simple.
Recommendation: Use character first name or last name and a number (example: cade1). In general, Nova does not like file names that include special characters (@ ! _ – $ %, etc.).