Downloading and Uploading Images

[mitsuki lover]

Ok so I have been selecting pics for my yet to be gallery at
anime galleries dot net.At the bottom of each pic I noticed that they
have a download button.I tried it and when I did it came up with a
warning about viruses and an option to download or to save.
Also I have found the Save Picture As function on the computer.
My question is:
1.Which would be better to use to avoid direct linking and any viruses?
2.How do I upload it once I get it downloaded?