Hi
Hi Knica
You will need to complete and submit a sponsorship application for your mom which you can download here:
http://www.cic.gc.ca/english/information/applications/famcls.asp Yes, there is a minimum income that you must meet in order to qualify to sponsor her. I believe it is around $21,000 but someone else here will be able to tell you or you can find the information in the sponsorship guide. Your first step should be to read the sponsorship guide and the guide specific to the visa office where your mom would be applying. You will find them both if you go to the link. If you have any questions, there are lots of knowledgeable people here. Good luck.
The OP wants her mother to come as a visitor not an Immigrant. No she doesn't require any income but s/he should send a letter of support about what she will be responsible for during her mother's stay, food, shelter. S/he should check the web site of the office where the mother would be apply for her TRV (visitor visa) for their requirements.
PMM