Help making a SIMPLE website with NextGEN Gallery.

I am new to WordPress. I don’t care about the posts, blogs, comments or any of that. I want to setup a simple page with a black background, and a NextGEN Gallery where I can display around 25 images on a grid. I will put a simple logo at the top center of the page with an <img src> tag. I also need the gallery to use the TagCloud feature where users can search images based on their tag.

I have tried making a custom theme from scratch, but got caught up in adding plugin support in functions.php. This is an extremely simple site that only uses the gallery plugin. I can make the site locally without wordpress, but I need help doing it WITH wordpress.

Once it is made, how can I edit basic css and html on the page? Where is that file located? Please help me do this.

Thank you!