For example, if you want to set variable L to 8:Type the number you want to store to the variable. Then press STO> to get an arrow. Then type L (Press ALPHA L [above ")"]). You should see:8->L...
When the picture you want is on the graph screen, press 2ND and then DRAW (above PRGM). Scroll over to STO at the top. Then select the first option, StorePic. (Use the second option to see a stored...
You either use a shell, if the game is designed for a shell or you use the Asm( tag if not. Check your games documentation to learn if it uses a shell.