I am a green card holder but I want my husband who is a us citizen to file for a visa for my mother,how do we go about it?

It is doubtful whether there is a visa for your mother that fits the purpose that you wish. Typically a visiting visa is for a parent who only wants to help out for a short period of time. In your case, you appear to be contemplating a long-term arrangement. That is not the purpose of a visiting visa. You are not eligible to sponsor her for permanent residence as you are only a green card holder. Your husband does not have the relationship to sponsor her for permanent residence. In the event that you change your plans and decide that your mother will only visit a short time to assist you, she would apply for a visiting visa and your husband could supply the appropriate letter guarantees that your mother will not have to work to support herself along with an I-134 affidavit of support, proof of his income, assets, and tax return. Due to the limitations of the Lawyers.com Forums, Alan Lee, Esq.'s (the "Firm") participation in responding to questions posted herein does not constitute legal advice, nor legal representation of the person or entity posting a question. No Attorney/Client relationship is or shall be construed to be created hereby. The information provided herein by the Firm is general, and requires that the poster obtain specific legal advice from an attorney. The poster shall not rely upon the information provided herein as legal advice nor as the basis for making any decisions of legal consequence.