You wont ever be able to achieve much on paint.net, if you want to get better i would advise you download gimp for free or download photoshop. Then you will see a vast improvement in your work
Guys don't say "oh look at me im better and im a beginner" thats bull shit lol some people are better than others but it doesn't mean they suck let this guy download gimp or PS and maybe he'll be better than you guys so don't go off spamming on here that your a beginner and better :/ BTW on the sig its nor really good but this is what i expect from a beginner so i give it a 3/5 go download gimp or Photoshop and i guarantee you'll get better lol
For a beginner I would say 3.5/5.
One rule of thumb though.
In a sig only yse your 1 render cause now you have 2 focals.
Just really hard to balance more then one render and make it look good.
Another pointer is try making them smaller.
Try 400x135 pixels.
Keep at it though and you will improve.
PM me if you want a portable vrsion of PS CS4 its free and it doesnt require cd key it also only less than 200 mb its what im using right now you can also copy the file to a usb and run it on any pc .Just pm me if you want the link.