Terrible in many ways.
The rotmg text is terrible, the background's dots don't fit too well, the sizes are quite weird for a signature, which is an issue cause most of the space is left unused.
The A of creating needs some additional work, it looks messy instead of fancy.
The colors are fine at least.
Seriously, why do people keep saying they made stuff in "just 5 minutes" ?
It shows you don't care, you prefer to complete whatever you have in mind rather than doing it right, or maybe it's just an excuse when you know it could've been a much more detailed work.
By the way, in between the making, hosting of the image, setting it as signature and posting it on the forum, i sincerely doubt (unless you were trying to do some kind of speedrun) that it actually took you 5 minutes or less.
What to do to improve: put more time into your works, choose the correct canvas, keep it simple.