cant get 8gb micro sd to work!

I have been unable to get my 8gb mirco sd to work.  I can’t load anything onto it.  My computer tells me I have to format it before I can use it, then it says it is write protected when I tell it to format.  I bought it at Walmart, and have never been able to get it to work.  Please tell me what I am doing wrong. :slight_smile: