How Do I Get My Own Ringers From My Computer On My Phone? Im With Bell And I Have The Samsung Instinct.?

Is there a way to get my own ringers from my computer onto my phone?
I used a micro sd card and put it in my computer and there is no folder for ringers. I am able to put music and photos and stuff, but im just wondering about ringtones.
I have a feeling that Bell is like Telus and doesnt let you put your own ringtones on ur phone, cos they want you to buy them from their over priced store. Is that true?
If it is, is there an alternate way to "bypass" this?