Every how many miles do I change the oil on a vstar 1100

3000 to 5000 miles is the range. 3000 miles city driving or up to 5000 miles touring miles. Some people change yearly or at 2000 miles. That is probably excessive and wasteful (of money and oil). Typically if you drive your motorcycle a lot, you will sense when it is running louder and with more vibration. That is how the motorcycle tells you that it wants an oil change.
You can use any oil that is JASO MA certified motorcycle oil. 10w-40 for cold climate. 20w-50 for warm climate/touring. Car oils use different additives and may cause scoring in certain types of cam bearings. Do not use any oil that says " Energy Conserving " on the label . It will shorten the life of your wet clutch and transmission gears. If you choose Synthetic oils, they will help your bike run cooler and shift easier. Shell Rotella T and Rotella T Synthetic 15w-40 are inexpensive JASO MA oils. You will need 4 quarts of oil, an aluminum drain plug washer, and a filter. Pour in 3.3 quarts , run the motor, and check the oil level . Top up as needed.