I have blood in my urine can someone please give me some common possibilities of what it could be?

Most likely. Most likely urinary tract infection. Other possibilities: kidney stone (usually very painful), menstual blood can contaminate the urine. If you are older than 40, then tumors of the urinary tract, although much less common, can cause hematuria. You should see a doctor, your primary care physician, if you see blood in your urine.
Various. The most common reason is a urinary tract infection but this could also be from a kidney stone, bleeding problem like low platelets or a clotting abnormality, cancer in the genitourinary tract or blood coming from the vaginal area in women. You should see a doctor to have this evaluated.