It's a little difficult for me to give you feedback for stuff on Pixlr because I don't use the site to make avatars or banners anymore. I'd be able to give you a better review if you were using photoshop.
With your first one, it seems like you were trying to make it cloudy green. For that, it's best to use brushes to create that smoke and fog before you add the effects to it.
Your second one has too much contrast. I see what you're trying to do by making pop out with highlights and shadows. Focus on doing just that. Have your focal point be at the ring which should give off a bright light and then just work on shading after that.
For both of these, you'll need a layer mask to make it all look clean, but unfortunately, Pixlr doesn't have that.
I'm not sure what kinda Pixlr you're using, but this is the site:
https://pixlr.com/x/#home