Can anyone explain to me how to type letters with accents on a PC word document, please; what is the X- system on a PC, MS word doc?
eg ĉ ĝ

Bonvenon! The x-system ("ikso-sistemo") just means type x after any letter that has a hat (think of a letter reaching for a hat), so that ĉ is written cx, and so on.

Apart from downloading programs like Ek, one way to convert text written using the x-system is the Melbourne notepad, which I have often used myself.
You can also create special combinations of characters in the Word program eg Alt-C can be ĉ.