Adding hues to images with PSP8

Hi. New to this community and I searched the memories for this, but didn't find anything. I hope it's okay to post. I was just wondering if someone could tell me how to add hues to an image and make it rainbow-colored, for example.

Some examples (probably not the clearest ones, but I can't find any other such images on my comp at the moment):



By starbuck42, [Maker unknown], frowninghour, space_coyote513.

Additionally, I'd appreciate it if someone could tell me how to give images a soft, one-toned look, as in the following, by starbuck42 and _jems_, respectively:



Thank you ever so much!