Connection Problems Majoris. The ugliest constellation.

[Bigheart]

So here i am in my house, looking at all these beautiful computer parts, when i realize that all i have to connect to the internet are some old phone lines, power lines, and three coaxial cables for 4 rooms. I want to try and run Deca adapters in the rooms without a modem but im not sure exactly how that works, and powerline, while easier for me to manage, is rather expensive if i want a quality connection. What should i do since i have no etherner ports? Thank you all for replying in advance.