Welcome to the graphic community, I think you have made some nice steps initially but let's help you refine them a bit more.
For the purposes of time I'll be only using the first example. This is a graphics forum, so I'd imagine the majority of us are visual learners, so I always find it better to alter a graphic that is asking for constructive criticism to show what I would potentially do if I was making the same image.
First of all, I shrunk the image down. 200 x 275 is a torn profile picture resolution. Shrinking it down helps you visualise how it will look like on someones profile. I then changed it to black and white because working with colour immediately can be overwhelming, usually I'd recommend working with a colour palette so you can picker tool on top of the black and white version instead of going straight in with colour if you are fairly new to graphics. When you do more graphics you'll get a knack for colour theory and have more of an idea what colours are complimentary etc
[image: cdn.discordapp.com] [image: cdn.discordapp.com]Here you can see a few issues. Try squinting your eyes, we're losing the second character and the background is too similar to Isabelle (trust me to know the name of the animal crossing character but not the other one lol). When a background is too similar to the main focus, we lose the direction of where our eyes should be looking, sometimes less detail is more pleasant.
First of all, I turned down the values, making the background black and white but also softer in detail. I then erased on the black and white effect a hole in the middle, which clearly highlights the point in the image I want the focus to be on. With that done, I made a new layer, I used black (Layer effect: Soft Light. Opacity: 100%) I used a feathered erase to cut the hole in the middle. This makes the main image stand out, while also giving the circle an almost 'halo' effect.
[image: cdn.discordapp.com] [image: cdn.discordapp.com]With the colour palette being dominantly red. On a new layer I used a gradient tool, making the bottom of the picture red, and as it gradually gets to the top the tone fades. This helps with the smoky/flame effect. I also used an image of 'flame spark' to add on top of the image as an overlay to really bump the effect of it being fire which helps with readability.
[image: images-wixmp-ed30a86b8c4ca887773594c2.wixmp.com] [image: cdn.discordapp.com]Though now the image looks more like a burning city at night than bricks. I couldn't do anything with the text as I'm only working on one layer here, but on another layer I highlight the text to give it more of a shine, while also adding some grey so it looks like soot.
[image: cdn.discordapp.com]Lastly I just overlayed a picture of lava, so it looks like it has run through the image which brings both background and foreground together. Though that is an optional step.
Just a disclaimer that this is how I would personally do it. This is just here to help you be more conscious about certain tricks and approaches you might have not thought about doing more than a 'follow this step by step guide'. Hopefully this helps, that being said, best of luck.