I would say do some online research, there are hundreds of websites for infused oils.
The usual oils of choice are groundnut oil, extra virgin olive oil, sweet almond oil and almond oil, but so long as it is not too strong smelling most oils will work.
The herb amount varies depending on whether you are using fresh or dried, it is usually around half the tum/bottle, or around, as long as you have enough oil at the end of it.
You then cover the herbs with the oil, making sure there is enough room to shake it slightly. You then seal the top tightly and leave it in a cool dark place for 2-6 weeks, 4-6 is recommended because it increases the fragrance and potency of the oil.
After the time is up, strain the herbs out of the liquid before placing the oil in a bottle. Stored in a cool place it can last for months up to years depending on the oils of choice.
Please be sure you clean the jars before use and that you know the proporties of the herbs and their origin before use, some can be dangerous.