there is no difference weather you are in bangladesh or any other country you can earn from adsense and most common way is to have a quality website and one adsense account then some quality traffic on that site
As long as your website is using the language that Adsense supports and doesn't violate the TOS, then I am sure you can put up at most three Adsense unit on your website. Then if your revenue has reached the payment threshold you can have your earnings sent in a cheque. It's that easy. Good luck!
You Create a website/ blog for people from Bangladesh and implement Google AdSense, or, if you talk very-good English language, you can open a website in English. You're paid very-good from Google AdSense.