Suggest you perform a leak down test, How to videos are on youtube.
If your lucky, all you have is a blown head gasket.
Which will require partial disassembly of the engine and required tools and replacement parts.
If not it gets worse from there.
A warped head ( same as above but also including, requiring machining at a machine shop )
A damaged head ( same as above but also requiring a replacement head )
A damaged block (requiring a replacement)
You will need a place to perform the work.
A shop manual will come in useful.
Do some research, watch some how to videos, get a better understanding of what is actually the issue.