could you give me some advice on where to look for the display
What kind of display? A 16 x 2 character display? A graphic LCD where you can draw stuff as well as show text?
Where in the world is Beng? Sending you to a supplier on the other side of the world isn't doing you any favors.
There is one small thing i would like to add as well but i really don't know if it's possible or not,i would like to get my hands on a blood oxygen sensor and give oxygen levels in the display as well.
Getting your hands on one, and being able to get sensible data from it, are two different things.
or which and how wireless technologies work in microcontrollers
You know, there are no rules against reading ahead. In fact, if you ask, I'll bet it's even encouraged.