You can get your teeth cleaned, polished, and bleaching done to get rid of yellow teeth. Spots on teeth need to be examined most probably it might be stains which can be treated.

Yellowness of teeth is the result of plaque and calculus deposition and if you have habit of any tobacco/smoking than its result also stains/ yellowness. Others coz of yellowness are fast food and carbonated drink, etc. Spot is may be caries. Please consult dentist for oral prophylaxis and if required than bleaching and restoration (filling).

Yellowness in teeth can be due to a lot of factors, most importantly its due to "plaque" which is nothing but a layer of debris on the surface of the enamel due to inadequate brushing. This layer calcifies over time and forms bands called "tartar". Other reason is the diet- at times tea and coffee and colour food stuff tend to stain teeth as well. Visit a dentist, who will evaluate the cause of yellowness. Scaling is a procedure which can remove surface deposits using ultrasonic energy and bring out the natural colour of your teeth. This is usually followed by polishing. Another procedure which could be helpful is teeth whitening or bleaching which helps to lighten the shade of your teeth.