I suspect this will be moved to G&A soon enough, but to make decent sigs and avies you can download
GIMP for free. Or, if you want to spend almost $1,000 USD, you can buy Adobe Photoshop CS3. You can also get older versions for less, but CS3 is worth buying. Reliable, and doesn't freeze on me, while GIMP froze on me on a regular occasion. But not all the time.
Avatar: In memory of ieatwyverns <3
Thank you, Vasco <3