how can I do this?
Command line. avrdude. For example, this reads the EEPROM from an ATtiny13 and saves the contents into a file named dump.txt ...
avrdude -p attiny13 -c stk500v1 -P \.\COM14 -b 57600 -U eeprom:r:dump.txt:h
Changing fuses is like building fine furniture. One wrong move and the piece is ruined.
First get comfortable reading the fuses from the targetA. Then get comfortable writing to FlashA. Next determine exactly what the fuses should be. RepeatB. If you get the fuses wrong the processor can be left in a state where only a "high voltage" programmer can resurrect it. Finally, change the fusesC.
Continuing with the woodworking analogy...
A Practice using the tool.
B Measure twice.
C Cut once.