#1 - if you are looking on a website at a picture the website has - you can save it by right-clicking the picture and going to "save picture as" and save it on your harddrive.
#2 - if the portion of the website you want to sve / coppy is text you can probably highlight it and copy and paste it.
#3 - If the portin of the site you want to save is both text and pitures or any combination of just text and or just pictures and you want to keep the formatting and everythign else, then do as people have said and use printscreen and paste into paint. ONCE you do that, use the paint tools to highlight the sectino of the page (now a picture) you want to keep and go to edit > copy. Then make a new paint file and goto edit > paste. File > save. DONE!
If neither of those is what you would like, then please enlighten us with more detail about what you are specifically trying to do, or how you want to use the end product. Feel free to leave out the details about you wanting to pine over your ex-girlfriends picture on myspace or how you just have to save to cool new pron you just found. No need for any details other then your problem.
Also note that none of this have anything to do with your OS, and should even be independant of browser. You will want to - or may want to keep in mind that most websites are copywrited and you need permission :cough: before using their site or pictures in any way.