How do you take glucosamine?

Orally. This is usually available otc in pill/tablet form and is taken orally. (glucosamine/chondroitin). For dosing, follow the lable or manufacturers recommendaitons.
Daily. The combination of glucosamine and chondroitin has been shown in studies to (1) provide a degree of pain relief in the short term, and (2) trigger growth of new cartilage when taken for at least two years straight. So it can help you pain and reverse some of the chronic damage. You can find this in the health food store. MSM is not necessary and adds to the cost of the product.
By mouth. Seriously, most studies suggest a daily dose of 1, 500 mg daily for a period of 3 months before deciding if it has any benefits.