there is no formal way to make payment from ethiopia unless you have access to credit card, alternative is if you know some one living in china or currency exchangers(black market) you can contact the seller of the item you want from aliexpress and ask him if he can accept payment offline via wechat or bank transfer, if he agrees you can make the payment through the people i mentioned above. for the delivery dhl, ups, fedx, aramex, ems are available but are expensive but fast, they can deliver in about 5 days, other methods include via post, they say delivery takes 20-40 or 30-50 days, but in reality they takes at least a month but usually more than 2 month but they are very cheap even some are free. another alternative is to ask if the sell could send it locally(to a chinese address) and make him send to one of the expresses that work between china and ethiopia, contact them and have them send it to you, this way its cheaper and shipping time takes roughly about 3 weeks