To insert an image, click the picture icon (the one on the left side of the chain icon) or press Ctrl+P while you're writing, then insert the link of your image. This will add IMG tags ([img]*your image URL*[/img]) to your writing without having to manually add them yourself.
Here I'll give you an example of how to apply it, with two images of mine.
Additionally, seeing as you use Flickr to upload your images, the link would be the one that starts with live.staticflickr.com rather than just flickr.com. I myself never used Flickr but I'm sure when you upload images on Flickr, there should be an option that says 'Image URL' with a link beside it. Copy that link and paste here.
If I don't add IMG tags to insert my pictures, they'll simply appear as links like this:
*LINK*
*LINK*
But if I do, it'll appear as pictures like this:
If you want to put it at the center of the page, simply add center tags by manually add them (["center"]["/center"] without the "), or click the align icon (the one on the left side of the "A" icon) and select 'center'). The format would be ["center"][img]*your image url*[/img]["/center"] without the " so they'll appear like this:
With these steps, your picture would appear like this:
Not so easy, I know, but it's quite a game changer you know
