How can I learn to build my own computer with Arm processors?

Arm don't sell any actual physical processors (well except for some high end development boards). They sell intellectual property, they enable others to build a system on a chip easily with what they are interested in. In the past one could get a processor and some memory and and some other chips and stick them on a circuit board probably with one's own FPGA to do what one wanted. Today most of that can be stuck onto a single chip, instead of a physical chips to stick on a board one licences IP and fits it into a SoC, the board it is put on is there mostly to provide human sized sockets.

Arm don't sell any actual physical processors (well except for some high end development boards). They sell intellectual property, they enable others to build a system on a chip easily with what they are interested in. In the past one could get a processor and some memory and and some other chips and stick them on a circuit board probably with one's own FPGA to do what one wanted. Today most of that can be stuck onto a single chip, instead of a physical chips to stick on a board one licences IP and fits it into a SoC, the board it is put on is there mostly to provide human sized sockets.

Thanks a lot deith