Remember when you have an ester, the first part of the name comes from the alcohol and the second part comes from the carboxylic acid used.
Ethyl propanoate is therefore CH3CH2COOCH2CH3, since ethyl implies ethanol (CH3CH2OH) and propanoate implies propanoic acid (CH3CH2COOH)
You can use the n+1 rule to determine the splitting of a peak. If there are ‘n’ non-equivalent hydrogens adjacent to a particular environment, then the signal for this environment will be split ‘n+1’ times.
Take for example a CH2 group sandwiched between a CH3 and a CHO group. The CH2 is adjacent to a total of 4 hydrogen atoms (3 from the CH3 and 1 from the CHO), so the signal due to the CH2 will be split 5 times.
Going from left to right and using the n+1 rule, can you determine the splitting patterns of each peak?