Given you asked about "commands for refresh" I assume you want to draw something on the screen.
You can check
https://github.com/pmartin/pocketbook-demo. Follow demo01, maybe skip 02 and 03, check 04.
Other than that, try to find small programs on GitHub and maybe check programs from
https://sourceforge.net/p/pocketbook...svn/HEAD/tree/. They may be old, but the SDK hasn't changed much.
There are several projects for programming in languages other than C/C++ but I'm not sure how easy it would be to use them. Maybe it is better to play around with C/C++ and SDK first. These other projects are usually simple wrappers for the same SDK.
Also, check
https://www.mobileread.com/forums/sh...d.php?t=353991. In addition to Go, Python, Eiffel wrappers there is
https://github.com/OliverHaag/rust-inkview for Rust.
Note to self: really think about writing a simple how to guide...