Can someone show all the work and explain what's going on

Write a program to add two 4-byte numbers that are stored at $1000-$1003 and $1004-$1007, and store the sum at $1010-$1013. Addition starts from the LSB and proceeds toward MSB. org $1500 Idd $1002; add and save the least significant two bytes addd $1006;" std $1012;" Idaa $1001; add and save the second most significant bytes adca $1005:" staa $1011;" Idaa $1000; add and save the most significant bytes adca $1004;" staa $1010;" end