Its pretty simple actually.
To load an ASM file click on the Open button and choose the file.
Once the asm file has loaded click on the compile button to convert the asm file to 8085 machine code
Then click execute to run the code, The output will be seen on the registers and flags.
You can also put breakpoints by clicking on left of an instruction. If execution reaches that instruction then the execution will stop and you can resume by clicking execute again or single step by pressing the step button.
You can directly edit a memory cell by double clicking on it.
You can write new ASM code using the text editor at the bottom and execute it if you wish.