if your phone is like mine, it will only let you set songs that are 300kb and less as a ringtone. My phone is the black jack 2 which is supposedly this awesome phone, but kills me i can only use partials as ring tones. again, try www.cellsea.com and search your song, make sure the file size is the correct size by clicking on it and seeing the size on the new page that comes up, and click download.
My next question is how are you trying to put them on your phone? i have only done it by downloading it and transfering it to my phone using the data cable....