Hi Candace, Thanks for contacting us. There are a couple of things you can try, however restoring noisy and grainy images is generally quite difficult to achieve. Within the Pro tab > Pro Editor tool > Pixlr Editor there is the Filter menu > Denoise option, however this has quite a subtle impact. This, in combination with using the Filter menu > Unsharp Mask, and the Blur tool (the blue raindrop icon on the side toolbar), will be your best tools.
There are a number of video tutorials on YouTube on how to get the most out of Pixlr, such as this one which focuses on these tools. Let us know if we can be of any further assistance!