Yunnan is a province in the South West of China. It's a relatively poor area. Hitchhiking is quite doable - the thumb sign is widely understood. Hardly anyone speaks any English though.
From/to Laos
Coming from Laos, Mungla will probably be the first city you enter. It's likely that ATMs don't work for you, so make sure you have some cash, there are guesthouses for 40 yuan. Buying a map of Yunnan (10 yuan, in Chinese only) and a dictionary (18 yuan) will prove to be very useful later on. Kunming is still 866 kilometers away.