I am changing oil without a manual need help. what weight and how much oil is needed for a Honda xl80 motorcycle?

You need to use 10w30 Synthetic in your Honda. The amount can be determined by parking the bike on a level surface, draining the oil. Pour in 1/2 quart of oil. Check the oil level and add as necessary to fill it up as shown on the dipstick. Click the link to get yourself a shop manual.