I've had some luck experimenting with the New Blogger. I think I've got a few things under control now. I'll see as I go what glitches I run into, but so far, so good.
Inside a cathedral it's often pretty dark. If it's sunny outside, one thing you can attempt to take decent picture of is stained glass. Without using a flash, anyway, which is something I don't do much.
Or you can stick to taking photos of features on the exterior of the building.
Above is a photo of the rose window in the north wing of the transept at Notre-Dame. In other words, it's north facing, so there's less light shining through in in the afternoon that through the south-facing window across from it, below.
If neither photo seems very much in focus to you, remember that they were taken 13 years ago, using a camera of that time. Besides, when you look at stained-glass windows from a distance, you don't see much clear detail anyway. I also don't use a tripod in such situations. The colors are nice.
Here's one more photo of Notre-Dame before the fire burned the roof off and the steeple fell.
P.S. I want to show you what I work with to prepare my blog posts. A lot of the work is done in what is called "compose mode" and the photos and text look approximately what you see when you open the blog in your browser. However, photos need to be resized and placed in the blog window where you want them. I do that work in "HTML mode" on screens that look like this one. It shows today's post, and if you look you can see my text in it. The rest is HTML code and it takes some getting used to before you can work with it with confidence. Actually, I had already cleaned this code up a little by adding some line breaks to make it more readable.
This morning I'm trying to figure out how to do one of the slideshows I've been posting for a couple of year now. I first upload the slideshow, in mp4 format, to YouTube, and then YouTube gives me some code I can use to "embed" the video in my blog post. Or that's how it used to work. In the new Blogger interface, it doesn't work any more. There must be some other way to include a slideshow in a blog post...