OO, those are hard programs to use! o.O"
Personally I'd recommend Krita, although it's a bit hard to use due to it's lack of a hand tool...
krita.org/en/features/highligh…It kinda looks like Photoshop, and it's open-source (free).
There's also FireAlpaca, (
firealpaca.com/) Gimp (
www.gimp.org/)- both of which are free. ;w;
None of them have viruses- lots of people use FireAlpaca and Gimp, and I can personally vouch for the safety of Krita, which I downloaded myself. xD
If you want to use more 'advanced' programs, you could try Paint Tool Sai, Clip Studio Paint/ Manga Studio, Autodesk Sketchbook (there's also a free version of this but it's... less useful), Adobe Illustrator, Adobe Photoshop, Corel Painter, or any other program someone else mentions here on deviantArt. : P
Is there anything you have a particularly hard time with? Btw, do you use a tablet or a mouse? xD