The problem I had was that i couldnt locate the folder for the zipalin command. Try this path
computer > local disk (c:) >Users > (name of user) > AppData > Local > Android > sdk
use the tools folder to open the command. If you have an issue when trying to input the info in the command window then it is because you need to transfer the 'zipaline' file from the 'build tools' folder into the 'tools' folder which can be found in the same place as the tools folder (within the sdk file).
for further info if you have problem, read this forum