Hello Quang Tu, Both of the sounds are made in the same way. The lips start together, teeth apart and then the lips are pushed open with air. The only difference is that the 'B' is voiced and the 'P' is unvoiced. If you hold your throat near the Adam's Apple (lump), you will feel vibration if you say 'B' but no vibration with 'P'. You will often hear 'b' in words but 'p' is harder. You need to listen for the other sounds. Try listening to minimal pairs like 'Bob' and 'Pop' to train your ears. Also other parts of the word often change their sound so you can tell this way. If you have a verb ending in 'b' - in the past tense the -ed ending will sound like a 'd' (robbed) but a with a verb ending in 'p' the 'd' will sound like a 't' (dropped) I hope this helps Bob

P is a voiceless sound. You can find many videos on youtube that explain how to make those sounds.

It will take time. When pronouncing B it is softer on the lips than P. With P you are pushing the lips out harder to pronounce it. With all asian lanuages though, it's the letter R that is the hardest.